Chapter 43: Carpal Fractures and Dislocations

Chapter Authors

Andrew D. Duckworth, Jason Strelzow

Carpal Fractures and Dislocations

Introduction to Carpal Fractures and Dislocations

Carpal injuries most frequently occur in young active patients and are not very common overall. We talk about them and study them disproportionately more than their frequency because they can be difficult to manage. For instance, fractures of the scaphoid are notorious for nonunion and sometimes the fracture is initially not visible on radiographs. The diagnosis of true fractures among suspected scaphoid fractures remains a dilemma. Despite advances in imaging, there remains controversy as even the most sophisticated imaging has false positives and false negatives and because true fractures are uncommon. There is no consensus reference standard for true fractures. The use of clinical predictions rules and latent class analysis, accepting that the best we can do is to define and refine the probability of a fracture, may help. 

Nondisplaced scaphoid waist fractures have traditionally been treated in above-elbow casts including the thumb for nearly 3 months and issues with union persist. Screw fixation is an appealing option, but research suggests that with an accurate diagnosis of displacement, shorter, less cumbersome methods of immobilization may suffice. Proximal pole fractures and displaced waist fractures are more routinely operated on, while distal pole fractures are treated symptomatically. Perilunate dislocations and fracture–dislocations are serious injuries, but effective treatment can maintain a mobile, useful wrist. Intercarpal ligament injuries and carpal malalignment remain confusing and debatable with many options for patients and surgeons to consider, and many questions worthy of study. 

Pathoanatomy and Applied Anatomy Relating to Carpal Fractures and Dislocations

An understanding of the anatomy and kinematics of the eight carpal bones is essential for the diagnosis and management of carpal injuries. Advanced imaging techniques have increased our knowledge of the three-dimensional (3D) movements of the carpus, including their individual and combined contributions to wrist motion and stability. 

Bony Anatomy of Carpal Fractures and Dislocations

The carpus encompasses two rows of eight bones (Fig. 43-1) that serve as a bridge between the forearm and the hand, providing movement at the wrist joint, while also retaining a notable degree of stability. The proximal carpal row from radial to ulnar includes the scaphoid, lunate, and the triquetrum. It is referred to as the key intercalated segment between the forearm and the distal row of the carpus, which is relatively fixed to the metacarpals distally, because there are no direct tendon attachments to the proximal row and their movement results from the shape of the bones, their interaction with other bones, and the ligament attachments. Through these articulations the proximal carpal row provides wrist joint movement and congruency, as well as force transmission between the forearm and hand. To enable this to occur, the position and orientation of the scaphoid, lunate, and triquetrum is dynamic through the various ligamentous attachments, as the proximal row has no direct tendinous attachments. Although the pisiform bone may provide stability to the proximal carpal row through the pisotriquetral joint, it should not theoretically be considered to be within the proximal carpal row as it is a sesamoid bone enclosed within the sheath of the flexor carpi ulnaris tendon. 

The wrist is composed of two rows of bones that provide motion and transfer forces. C, capitate; H, hamate; L, lunate; S, scaphoid; T, triquetrum; P, pisiform; Td, trapezoid; Tm, trapezium.

The distal carpal row from radial to ulnar includes the trapezium, trapezoid, capitate, and the hamate. The distal row articulates with the proximal carpal row, and distally with the five metacarpals of the hand by forming a transverse arch on which they are supported. The trapezium articulates with the first metacarpal, the trapezoid with the second, the capitate with the third and the hamate articulates with the fourth and fifth. The capitate and trapezoid are tightly connected to the metacarpals, whereas there is 30 to 40 degrees of flexion–extension and rotation at the metacarpotrapezial joint. Motion at the distal carpal row is controlled by the extrinsic wrist flexors and extensors. 

Ligamentous Anatomy of Carpal Fractures and Dislocations

The ligaments of the wrist are predominantly contained within the joint capsule. The inherent stability of the carpal rows, combined with the degree of movement achieved at the wrist joint, is predominantly due to the support of the extrinsic (Table 43-1) and intrinsic (Table 43-2) ligaments that reinforce the capsule of the carpus. Buijze et al. reviewed 58 anatomical studies and found that apart from the scaphocapitate ligament, the carpal ligaments are not described consistently. 

Extrinsic Ligaments

The extrinsic ligaments of the carpus (Fig. 43-2) connect the carpal bones to the forearm bones (proximally) and the metacarpals (distally) (see Table 43-1). They are often difficult to distinguish from the fibrous capsule of the wrist on dissection. However, the extrinsic ligaments overlie the articulations of the joint and are frequently divided according to their anatomic position as palmar, dorsal, and collateral ligaments. 

A: The extrinsic palmar ligaments of the carpus. B: The extrinsic dorsal ligaments of the carpus.

The extrinsic palmar radiocarpal ligaments (see Fig. 43-2A) include the transverse carpal, radioscaphocapitate (RSC), radioscapholunate (ligament of Testut; RSL), radial collateral, long radiolunate (radiolunotriquetral; RLT), and the short radiolunate ligaments. The extrinsic ulnocarpal ligaments include the ulnotriquetral (dorsal and palmar), ulnolunate, and ulnocapitate ligaments. These palmar ligaments predominantly originate from a lateral position on the radial–palmar facet of the radial styloid and head in a distal ulnar direction, where they assemble with the palmar ulnocarpal ligaments originating medially from the distal ulna and triangular fibrocartilage complex (TFCC). The strong oblique extrinsic palmar radial ligaments prevent the carpus from translating medially on the angulated slope of the distal radius through two V-shaped ligamentous bands. One is proximal (long radiolunate, radioscapholunate, ulnolunate, ulnotriquetral) and connects the forearm to the proximal carpal row and one is distal (radioscaphocapitate, ulnocapitate) and connects the forearm to the distal carpal row. Between the radial and ulnar palmar ligaments there is a V-shaped interligamentous sulcus over the capitolunate articulation, which is an interval of capsular weakness known as the space of Poirier. Maximal space is seen when the wrist is dorsiflexed, with the space almost disappearing in palmar flexion. This is of clinical relevance during dorsal dislocations as it is through this area of weakness that the lunate displaces into the carpal canal. The arcuate ligament is found in the central third of the palmar joint capsule and is thought to be formed from the interdigitation of transverse fibers of the radioscaphocapitate, ulnocapitate, triquetrocapitate, and volar scaphotriquetral ligaments. This ligament forms a support sling for the midcarpal region, in particular the head of the capitate, which is thought to improve the midcarpal movement while also delivering carpal stability. Alternate names for the arcuate ligament include the deltoid ligament, palmar distal V ligament, or the Weitbrecht oblique ligament. Controversy exists regarding the existence of individual forms of some of the ligaments that make up the arcuate ligament, in particular the volar scaphotriquetral ligament. 

The extrinsic dorsal carpal ligaments (see Fig. 43-2B) include the dorsal radiocarpal (DRC) ligament, which may also be known as the dorsal radioulnotriquetral ligament or the dorsal radiotriquetral ligament, and the dorsal intercarpal ligament, which form a V-shaped configuration. The ulnodorsal capsule of the wrist is reinforced by the ulnolunate and ulnotriquetral ligaments and the floors of the fifth and sixth extensor compartments. Some studies have suggested an essential role of the dorsal carpal ligaments in scapholunate stability. 

Intrinsic Ligaments

The intrinsic ligaments connect the individual carpal bones to one another (Fig. 43-3; see Table 43-2). The ligaments are intra-articular short fibers that connect and hold the carpal bones of both the proximal or distal rows to each other. There is a contiguous merging of the interosseous ligaments with the joint articular cartilage. The intrinsic ligaments include the palmar midcarpal ligaments (scaphotrapeziotrapezoid, scaphocapitate, triquetrocapitate, triquetrohamate), the proximal interosseous ligaments (scapholunate, lunotriquetral), and the distal interosseous ligaments (trapeziotrapezoid, trapeziocapitate, capitohamate). Ligaments associated with the pisiform include the pisotriquetral ligament that bridges the pisotriquetral joint, and the pisohamate ligament, which is an extension of flexor carpi ulnaris. 

A: The palmar intrinsic ligaments: scaphotrapeziotrapezoid ligament (STT), scaphocapitate ligament (SC), triquetrocapitate ligament (TC), and triquetrohamate ligament (TH). B: The dorsal intrinsic ligaments: capitohamate ligament (CH), capitotrapezoid ligament (CT), lunotriquetral ligament (LT), scapholunate ligament (SL), trapeziotrapezoid ligament (TT). The dorsal intercarpal ligament is not shown.

On the radial side of the wrist the V-shaped scaphotrapezium–trapezoid ligament is found, providing stability to the scaphoid–trapezium–trapezoid articulation as well as the scaphoid itself. The V shape is from the scaphotrapezial component of the ligament. Although insertion on the trapezoid bone is contested, recent studies have suggested the existence of two distinct ligaments: the scaphotrapezoid and scaphotrapezium ligaments, with the former thinner and less robust. However, some have suggested that the soft tissue present is a capsule. Adjacent to the scaphotrapezium–trapezoid ligament is the scaphocapitate, which is a large robust ligament that provides midcarpal stability with fibers running parallel to the radioscaphocapitate ligament. One recent study analyzed eight fresh-frozen cadavers using 3D CT and cryomicrotome imaging to better define the osseous and ligamentous anatomy of the scaphoid. They concluded that the scaphocapitate ligament was the thickest ligament of all those that attached to the scaphoid, with a mean thickness of 2.2 mm. On the ulnar side of the wrist, the remaining palmar midcarpal ligaments are the triquetrocapitate and triquetrohamate ligaments. 

The proximal interosseous scapholunate and lunotriquetral ligaments are found deep within the carpus and are considered the two most important intrinsic ligaments as they are critical to carpal stability. The scapholunate interosseous ligament is a strong, stiff, C-shaped ligament that plays a vital role in carpal stability, with the thick and strong dorsal portion containing transversely oriented collagen fascicles key to the stability of the scapholunate joint. The palmar/volar and proximal/central portions act as secondary stabilizers, contributing primarily to rotational stability of the joint. Recent studies have demonstrated that the scapholunate interosseous ligament is the primary stabilizer of the scapholunate joint, with the scaphotrapezium–trapezoid ligament and the radioscaphocapitate ligament being secondary stabilizers and the dorsal carpal ligaments likely having a tertiary role. The lunotriquetral ligament interdigitates with three extrinsic ligaments: the ulnotriquetral, ulnolunate, and radiolunate ligaments. The thickest and strongest zone of the lunotriquetral ligament is found palmarly. A stronger kinematic relationship than the scapholunate ligament is seen due to the tight association of its fibers. The scaphotriquetral ligament is a distal extension of the scapholunate and lunotriquetral ligaments. 

The distal interosseous ligaments have a comparable structure to the proximal interosseous ligaments, with both palmar and dorsal fibers. The trapeziotrapezoid and trapeziocapitate ligaments similarly span their respective articulations, but with the latter having a deep ligament that bridges the joint. The capitohamate ligament spans only the distal part of the capitohamate joint articulation and again is reinforced by a large deep ligament that has extensions to the middle and ring finger metacarpals. 

Neurovascular Anatomy of Carpal Fractures and Dislocations

The neurovascular supply to the carpus is through the regional vasculature and nerves. Innervation is via the anterior interosseous and the posterior interosseous nerves. Circulation to the carpus is comprised of an extraosseous and intraosseous vasculature via both dorsal and palmar vascular systems, which are branches of the radial, ulnar, anterior interosseous and deep palmar arch arteries (Fig. 43-4). The extraosseous arterial supply is formed by an anastomotic network of dorsal and palmar transverse arches connected longitudinally from their medial and lateral borders by the radial, ulnar, and anterior interosseous arteries. The three dorsal transverse arches of the carpus include the radiocarpal, the intercarpal, and the basal metacarpal arches. The three palmar transverse arches of the carpus include the radiocarpal, the intercarpal, and the deep palmar arches. For all of these arches, their presence in cadaveric specimens is inconsistent. 

Schematic drawing of the arterial supply of the palmar aspect of the carpus. Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch. 1, Palmar radiocarpal arch; 2, palmar branch of anterior interosseous artery; 3, palmar intercarpal arch; 4, deep palmar arch; 5, recurrent artery.

The incidence of avascular necrosis (AVN) following injury to the carpal bones is related to their complex intraosseous blood supply. Original work documented that the vascular supply of most carpal bones enters the distal half, leaving the proximal half at risk of AVN. The vascular supply of each carpal bone is shown in Table 43-3. From this, three general patterns of intraosseous vascularization have been described which help with identifying the carpal bones at risk of osteonecrosis. 

• The scaphoid, capitate, and about 20% of all lunates are supplied by a single vessel increasing their risk of AVN
• The trapezium, triquetrum, pisiform, and 80% of lunates receive nutrient arteries through two nonarticular surfaces and have consistent intraosseous anastomoses, therefore reducing the risk of AVN
• The trapezoid and 50% of hamates lack an intraosseous anastomosis and are at risk of avascular fragments

Kinematics of Carpal Fractures and Dislocations

The study of carpal kinematics began in the late 1800s using plain radiographs, and knowledge has advanced through in vitro cadaveric work, as well as employing advanced imaging techniques such as 3D CT. 

The biomechanics of the wrist joint need to allow for load transmission from the hand to the forearm and a wide range of motion, while maintaining stability throughout. Two predominant articulations are found at the wrist joint and include the proximal carpal bones (scaphoid, lunate, triquetrum) with the distal radius and ulna, which is considered as the key intercalated segment and provides principally extension and ulnar deviation at the wrist. The second articulation is between the proximal and distal carpal rows and provides predominantly flexion and radial deviation. Motion predominantly occurs in two planes, with flexion–extension at approximately 70 degrees in both directions, and radioulnar deviation at approximately 20 and 40 degrees, respectively. The adjacent radioulnar joint provides a substantial rotatory arc of approximately 140 degrees around the longitudinal axis of the forearm. 

Although many theories have been described, there are two predominant theories used to explain carpal kinematics, which are known as the columnar and oval ring or row theories. The columnar theory is the oldest, described by Navarro (Fig. 43-5). He observed motion between the proximal carpal row bones, predominantly from data on birds, and put forward the theory of three longitudinal columns: 

• A mobile lateral (radial) column consisting of the scaphoid, trapezium, and trapezoid
• A central flexion–extension column consisting of the lunate, capitate, and hamate
• A rotational medial (ulnar) column consisting of the triquetrum and pisiform

The columnar theory of carpal kinematics. C, Capitate; H, Hamate; L, Lunate; P, Pisiform; S, Scaphoid; T, Triquetrum; Td, Trapezoid; Tm, Trapezium.

This theory goes some way to explaining the load transmission of the wrist but not synchronous motion. Taleisnik put forward a modification of this theory by including the trapezium and trapezoid (i.e. lunate + distal carpal row) into the central column, as well as removing the pisiform from the medial column. With this theory, flexion and extension occur through the central column, but he suggested that the scaphoid was an essential stabilizer for the midcarpal joint (radial column), the triquetrum (triquetrohamate joint) was the pivot point for rotation of the carpus, and that radial and ulnar deviation was facilitated through rotation of the scaphoid laterally and the triquetrum medially. 

The alternative oval ring theory combines the theories of the carpal row and oval ring concept (Fig. 43-6). The key concepts for this theory include the proximal intercalated segment, variable geometry, as well as the synchronous and reciprocating motion of the carpal rows. What is key to providing versatility to the wrist joint, combined with the ability to remain stable throughout, is the proximal intercalated segment (proximal carpal row). The primary axis for the combined motion of the carpus has been found to be within the head/neck of the capitate, which is not a singular point, but rather an oblique screw axis. The scaphoid is found on an axis 45 degrees to the longitudinal axis that passes through the lunate and capitate, and provides stability to the midcarpal joint while also stabilizing the central column. By virtue of its obliquity, the scaphoid will flex when under compression and exerts a similar force on the lunate. The lunate, however, is also under the influence of the triquetrum, which inherently prefers to extend. For this reason, the lunate may be thought of being in a state of dynamic balance between two antagonists, tending to lie in the position of least mechanical potential energy. 

The oval (A) and row (B) theories of carpal kinematics. C, Capitate; H, Hamate; L, Lunate; P, Pisiform; S, Scaphoid; T, Triquetrum; Td, Trapezoid; Tm, Trapezium.

The movement of the individual components of the proximal carpal row allows the length and contour of the proximal carpal row to be dynamic, providing extreme movements at the wrist while also maintaining stability around the longitudinal axis. This concept is known as the variable geometry of the proximal carpal row. To provide such a degree of motion, the individual carpal bones are multirotational, moving not only up and down and back and forth, but also spinning and rolling about their own axes. 

During flexion and extension of the wrist, each carpal bone angulates in the same direction with nearly equal amplitude and in a synchronous fashion, a concept known as synchronous angulation (Fig. 43-7). However, the amplitude of movement is different for the bones of each column. Recent studies using 3D noninvasive imaging have reexamined previous work analyzing the radiocarpal and midcarpal contributions to wrist flexion and extension. Sarrafian et al. documented that 40% of wrist flexion is at the radiocarpal joint, with about 60% at the midcarpal joint, and that for wrist extension 66.5% is at the radiocarpal joint with 33.5% at the midcarpal joint. More recent studies have documented that in flexion 62% to 75% of wrist motion occurred at the radioscaphoid joint, with 31% to 50% at the radiolunate joint. In extension, 87% to 99% of wrist motion has been shown to occur at the radioscaphoid joint, with 52% to 68% at the radiolunate joint. 

Conjunct rotation of the entire proximal intercalated row occurs in flexion during radial deviation (upper left). The axes of the radius and carpal rows are collinear in neutral (middle left), and the proximal row extends with ulnar deviation (lower left). Angulatory excursions of the proximal and distal rows are essentially equal in amplitude and direction during extension (upper right) and flexion (lower right). This has been described as synchronous angulation.

During radioulnar deviation, the proximal row exhibits a secondary out-of-plane angulation (sagittal plane) in conjunction to the synchronous motion occurring in the coronal plane. In radial deviation, the proximal carpal row flexes and the capitate extends (reciprocal motion). Flexion of the obliquely orientated scaphoid, as the trapezium and trapezoid approach the radius, is transmitted through the dorsal scapholunate ligament and onto the lunate and triquetrum, when flexion is at 10 to 20 degrees. With ulnar deviation of the wrist, the proximal carpal row extends as the unique helicoid shape of the triquetrohamate joint forces the distal carpal row to translate dorsally, the hamate migrates proximally and the triquetrum tilts into extension. The inherent linkage of the triquetrum to the surrounding proximal carpal row brings the lunate with it, leading to an extension moment through the proximal row. The converse occurs during radial deviation. Recent studies have demonstrated that associated pronation (radial deviation) and supination (ulnar deviation) of the proximal carpal row is minimal. These studies have also demonstrated that radial and ulnar deviation occurred primarily at the midcarpal joint, accounting for about 60% and 85% of the movement, respectively. 

Pathoanatomy of Carpal Fractures and Dislocations

An injury to the carpus commonly occurs following a mechanism in which an axial compression force is applied to the wrist, commonly leading to hyperextension where the palmar ligaments undergo tension and the dorsal articulations are subject to shear stresses. It has been demonstrated that both the degree of force applied to the wrist and the degree of wrist radial or ulnar deviation will determine whether a ligament injury, a fracture, or both, occur. Minor injuries, such as ligamentous sprains, frequently result from a low-energy injury. However, one study has demonstrated a relationship between a low-energy simple fall in women and sustaining a scaphoid fracture. Higher-energy injuries that involve a more considerable force result in either a fracture to one or more of the carpal bones and/or a ligamentous disruption, with both intrinsic and extrinsic ligaments potentially involved. Variations in bone quality, the direction and magnitude of the deforming force, and the position of the wrist at the time of injury explain the variety of injuries that can occur. 

Carpal Fractures

Any shear strain that travels across the midcarpal joint is transferred through the scaphoid and may cause a fracture and/or dislocation. Fracture of the scaphoid has been shown to occur when the wrist is dorsiflexed to at least 95 degrees and radially deviated to at least 10 degrees. In this position the proximal pole of the scaphoid is held firmly between the radius, capitate, radioscaphocapitate ligament, and the palmar capsule (Fig. 43-8). With the wrist radially deviated, the radioscaphocapitate ligament is relaxed and unable to relieve the increasing force being applied to the radiopalmar aspect of the scaphoid. When axial loading and/or dorsal compression of the scaphoid occurs in this position, the scaphoid will fracture, most frequently through the waist as it is subject to the maximal bending movement and has a characteristically lower trabecular volume. 

The schematic above demonstrates the progression to fracture of the scaphoid during a hyperextension injury to the wrist. The proximal pole of the scaphoid is trapped between the radius and tense palmar extrinsic ligaments, with the force concentrated at the scaphoid waist leading to fracture.

The degree of force and position of the wrist at the time of injury are the likely determinants for the type and severity of the scaphoid fracture. Herbert suggested that wrist deviation may predict the location of the fracture as the line of the midcarpal joint crosses the proximal pole in radial deviation and the distal pole in ulnar deviation. Fractures of the waist are usually the result of shear forces across the scaphoid, while tubercle fractures appear to be caused by either compression or avulsion. Compson suggested that the size of a proximal pole fracture was dependent on the level of the proximal extent of the joint facet with the capitate, which is the most variable aspect of scaphoid anatomy. Smaller proximal pole fractures can also be caused by an avulsion of the attachment of the scapholunate ligament. 

With an unstable displaced scaphoid fracture, the kinematics of the wrist is altered. Joint compressive forces, trapezium–scaphoid shear stress and capitolunate rotation moments all act upon the scaphoid, leading to a dissociation of the proximal and distal carpal rows that permits the natural tendency of the two carpal rows to fail by collapsing, assuming a lunate-extended posture. The scaphoid will assume an anteverted position, the lunate and triquetrum may subluxate forward and rotate dorsally, and the capitate and hamate subluxate dorsally and proximally, producing the dorsal intercalated segment instability (DISI) deformity (see section Carpal Ligament Injuries). This is demonstrated clinically by the collapse pattern seen with chronic scaphoid nonunion, a condition known as scaphoid nonunion advanced collapse (SNAC) appearing as a DISI deformity. The proximal and distal fracture fragments can collapse giving a characteristic flexed or “humpback” position on radiographs with an intrascaphoid angle of greater than approximately 30 degrees. 

Fractures of the capitate represent a relatively infrequent carpal fracture (1% to 2%). These injuries may be classified according to the pattern of fracture and are commonly associated with perilunate injuries. It has been suggested that fracture of the capitate occurs through one of three potential mechanisms: 

• Scaphocapitate syndrome: Occurs with a violent blow directed to the radial styloid which first fractures the scaphoid and then the capitate but produces no dislocation. The capitate fragment can be rotated 90 to 180 degrees, with the articular surface displaced anteriorly or facing the fracture surface of the capitate neck. Some have questioned the nomenclature with reports suggesting a scaphoid fracture does not always occur.
• Anvil mechanism: An axial load with the wrist in dorsiflexion, forcing the capitate onto the dorsal rim of the radius. The dorsal border of the radius will impinge on the capitate and cause a fracture through its waist.
• Direct blow or crush injury.

Fracture of the lunate commonly occurs following a hyperextension injury to the wrist. In extension, the lunate is displaced onto the palmar aspect of the lunate fossa and rotated dorsally. The capitate pushes against the palmar aspect of the lunate and at the same time moves it into an ulnar direction, which is countered by the radioscapholunate ligament. When the forearm is pronated and there is an ulnar minus variant, the support offered by the TFCC and ulnar head will be reduced and the compressive stresses across the proximal convexity of the lunate are altered between the TFCC and radial articular surface. The reduced ulnar support may also allow proximal displacement of the triquetrum placing further tensile stress on the lunate surface through the lunotriquetral ligament. This chain of events can eventually result in a transverse fracture of the lunate in the sagittal plane. 

Avulsions of the dorsal pole of the lunate are often associated with scapholunate dissociation (SLD) and are thus likely secondary to tension placed on the scapholunate ligament. Avulsion fractures of the ulnar aspect of the palmar pole of the lunate are frequently associated with a perilunate dislocation and are thus likely secondary to tension placed on the lunotriquetral ligament (see below). 

In the above scenarios, stress may be placed on the vasculature of the lunate (see Table 43-3) prior to a fracture occurring, leading to the development of Kienböck’s disease. There is considerable evidence that the mechanisms of fracture are also associated with the development of Kienböck’s disease, with Kienböck’s disease presumed to be secondary to trauma, ulnar variance, and impaired vascularity. 

Fractures of the hamate are typically the result of direct compression. These injuries represent less than 5% of carpal fractures. The classification is based on the location of the fracture: body fractures and hook of hamate fractures. Grip injuries resulting from the hook of the hamate being directly compressed against a handheld object as well as avulsion injuries of the pisohamate ligament have been reported. 

Three main variants of pisiform fractures occur: avulsion variants with flexor carpi ulnaris tendon contraction, triquetral-pisiform impaction, and as a result of a direct blow. Diagnosis can be difficult and careful radiographic evaluation is required. 

A rare injury, typically seen in combination with associated carpal injuries or carpometacarpal dislocation. The position of the trapezoid offers a degree of protection within the distal carpal row. Injury mechanisms are typically high–energy-involving direct trauma, axial loading, and/or forced extension/flexion. 

Fractures of the trapezium account for 1% to 5% of all carpal fractures. These injuries can result from axial loading, traction, and avulsion-type mechanisms. Fractures of the body of the trapezium, trapezial ridge, as well as fracture–dislocation patterns are described. Associated injuries to the hamate and scaphoid are well described. 

After scaphoid fractures, isolated fractures of the triquetrum are the second most frequent carpal fracture. Injuries can be described as volar avulsion fractures, fractures of the dorsal cortex, and triquetral body injuries. Dorsal cortical fractures are thought to result from avulsions of the radiotriquetral and dorsal intercarpal ligaments; however, other authors propose a compression mechanism against the hamate or ulnar styloid. Additional fracture patterns may result from an ulnar deviated wrist forced into dorsiflexion. 

Carpal Ligament Injuries

Carpal instability usually follows a high-energy injury leading to the wrist undergoing a force associated with hyperextension, ulnar deviation, and intercarpal supination. This can lead to an interruption of the oval ring, commonly in the proximal carpal row, leading to instability. The most common pattern of injury is associated with a perilunate dislocation or fracture–dislocation (see below). 

Although several systems exist, three interrelated classification systems are commonly used for defining carpal instability and are useful in understanding the pathoanatomy of the injury. The three classifications include intercalated segment instability static versus dynamic, and dissociative versus nondissociative (Table 43-4). Linscheid described instability in relation to the appearance of the lunate and the intercalated segment on standard lateral radiographs (Fig. 43-9). When the dynamic kinematic relationship between the scaphoid, lunate, and triquetrum is disrupted by either a fracture and/or ligamentous injury, instability of the wrist ensues with loss of synchronous motion and intercarpal contact patterns. The lunate will flex with loss of ulnar support from the triquetrum and when in a fixed position of flexion of greater than 15 degrees, volar intercalated segment instability (VISI) has occurred. When the opposite occurs and the lunate falls into fixed extension of more than 10 degrees, DISI has occurred. The fixed malpositioning of the lunate, even in radial and ulnar deviation of the wrist, affects the functioning of the proximal intercalated segment and thus the kinematics of the wrist. With persistent instability, degenerative changes will ensue as a consequence of increased shear forces and abnormal contact between the individual carpal bones. 

Schematic drawing of carpal instability. A: Normal longitudinal alignment of the carpal bones with the scaphoid axis at an approximately 45-degree angle to the axes of the capitate, lunate, and radius. B: DISI deformity (scapholunate angle >60 degrees). C: VISI deformity (scapholunate angle <30 degrees).

Dissociative instabilities of the carpus involve an isolated ligament disruption between two connected carpal bones (injury to major intrinsic ligament), with or without an associated bony disruption (e.g. SLD) with or without a fracture of the scaphoid. Nondissociative instabilities of the carpus maintain the connections between the carpal bones of the same row but include subluxations or incomplete dislocations of the entire carpus (radiocarpal subluxation or dislocation) that may be purely ligamentous (injury to major extrinsic ligament), but more commonly include a fragment of the distal radius. These dislocations are frequently a palmar or dorsal Barton fracture–dislocation, or a radial styloid fracture–dislocation (e.g. a chauffeur’s fracture). DISI and VISI instabilities may be either dissociative or nondissociative depending on the degree of damage to the ligamentous connections of the proximal carpal row. 

Static instability occurs when carpal malalignment and instability is found on standard PA and lateral radiographs of the wrist. With dynamic instability, carpal malalignment and instability is only apparent using specified clinical physical provocation tests and when stress radiographs are positive (normal standard radiographs). The term adaptive carpal instability relates to the development of carpal instability due to a cause unrelated to the carpus, for example, carpal malalignment following a severe malunion of a distal radius fracture. 

Perilunate Dislocation and Fracture–Dislocation

Perilunate dislocations and fracture–dislocations predominantly follow a high-energy mechanism of hyperextension, ulnar deviation, and intercarpal supination injury to the wrist. There are rare cases of reversed perilunate instability, when the wrist is pronated at the time of impact thus adding an external force to the hypothenar region, forcing the wrist into extension and radial deviation. For these cases the lunotriquetral ligament injury occurs first and the scapholunate ligament may remain intact. 

Perilunate dislocations can be subdivided into two subgroups,: 

• Lesser-arc perilunate dislocations: pure ligamentous injuries around the lunate
• Greater-arc perilunate dislocations: ligamentous injuries associated with a fracture of one or more of the bones around the lunate

Mayfield suggested that carpal instability predominantly occurs in relation to the lunate, which is the carpal keystone. He put forward a pathoanatomic classification associated with progressive perilunate instability from a radial to ulnar direction (Fig. 43-10): 

• Stage I: Scaphoid fracture, SLD, or both
  • As the distal carpal row is violently extended, supinated, and ulnarly deviated, the scaphotrapezium–trapezoid and scaphocapitate ligaments are tightened causing the scaphoid to extend. As the scaphoid extends, the scapholunate ligament transmits the force to the lunate, which cannot rotate as much as the scaphoid because it is constrained by the palmarly located radiolunate and ulnolunate ligaments. As a consequence, a scaphoid fracture or a progressive elongation and tearing of the scapholunate and palmar radioscaphocapitate ligaments may occur, potentially leading to complete SLD.
• Stage II: Lunocapitate dislocation
  • If the extension-supination force on the wrist persists once the proximal carpal row has been dislocated, transmission of the force distally to the capitate may lead to displacement and eventual dislocation dorsally through the space of Poirier. It is followed by the rest of the distal carpal row and the radial-most portion of the dislocated proximal carpal row. This may be the complete scaphoid or just its distal fragment.
• Stage III: Lunotriquetral disruption
  • If the extension-supination force to the wrist persists, once the capitate is displaced dorsally lunotriquetral (most common), ulnotriquetral, and/or triquetrum–hamate–capitate ligament disruptions may occur. Stage III is complete when the palmar lunotriquetral ligament, including the medial expansions of the long radiolunate ligament, is completely disrupted and the joint has been displaced. This results in a midcarpal dislocation with both the lunate and capitate no longer aligned with the articular surface of the radius.
• Stage IV: Lunate dislocation
  • If the extension-supination force to the wrist persists and the dorsally displaced capitate is pulled proximally, pressure is applied onto the dorsal aspect of the lunate, forcing it to dislocate in a palmar direction due to injury to the DRC ligament. As the palmar ligaments are much stronger than the dorsal capsule, such a dislocation seldom involves a pure palmar displacement of the lunate, but rather a variable degree of palmar rotation of the bone into the carpal tunnel using the intact palmar ligaments as a hinge.

The Mayfield stages of progressive perilunate instability. Stage I results in SL instability. Stages II to IV result in progressively worse perilunate instability.

Lunate dislocation is the end stage of progressive perilunate instability. Along with ligamentous disruptions, fractures of the radial styloid, scaphoid, capitate, and the ulnar styloid can occur. Importantly, these injuries exist along a spectrum representing minor ligamentous injuries all the way to complex osseoligamentous disruption. 

Assessment of Carpal Fractures and Dislocations

Epidemiology of Carpal Fractures and Dislocations

When compared to fractures of the distal radius and hand, fractures of the carpus are uncommon, particularly those injuries not involving the scaphoid. There are minimal data documenting the global epidemiology of these injuries. The majority of literature is in relation to the epidemiology of scaphoid fractures, which is discussed later. An issue with many of the epidemiologic studies in this area is that the majority of the data is collected retrospectively leading to inaccuracies in diagnosis and classification. Furthermore, many studies are performed with specific patient populations, for example, the military, leading to wide-ranging results regarding incidence, age, gender, and modes of injury. 

Using data that is presented in Chapter 6 on fracture epidemiology from the Edinburgh 2010–2011 database, carpal fractures are relatively frequent accounting for 2.8% of all fractures with an annual incidence of 37.5/10 population per year. From the early 1900s, Stimson quoted a prevalence for carpal fractures of 0.2% of all fractures, although he acknowledged that the number of carpal fractures, particularly those of the scaphoid, was probably higher. Data from the past 60 years is consistent, with a prevalence ranging from 2% to 3% of all fractures. 

The mean age at the time of injury for all carpal fractures ranges from 35 to 40 years and a male predominance is seen. Overall, fractures of the carpus have a type A fracture curve with a bimodal distribution involving younger males and older females. A fall from standing height accounts for almost two-thirds of all injuries, with other modes of injury including sports, direct blow, assault, and RTA. 

It is consistently documented that scaphoid fractures and fractures of the triquetrum account for over 90% of all carpal fractures, with injuries to the hamate, pisiform, lunate, capitate, trapezium, and trapezoid being rare. Fractures of the scaphoid, hamate, pisiform, and trapezium appear to occur predominantly in younger males, with the mean age ranging from 29 to 43 years and a male predominance ranging from 66% to 100%. These data are consistent with a type B fracture distribution curve (Fig. 43-11). Triquetral fractures appear to be a different fracture to other fractures of the carpus, occurring at a mean age of 51 years with an approximately equal gender distribution, thus most closely fitting a type A fracture distribution curve. One study analyzed the epidemiology of scaphoid fractures against that of the other carpal fractures and found youth and males to be associated with a fracture of the scaphoid. 

A type B fracture distribution curve for fractures of the scaphoid as seen in Edinburgh from 2007 to 2008. (Reprinted with permission from Duckworth AD, Jenkins PJ, Aitken SA, et al. Scaphoid fracture epidemiology. J Trauma Acute Care Surg. 2012;72(2):E41–E45.)

Injuries Associated with Carpal Fractures and Dislocations

Associated injuries are seen in approximately 7% of cases, with a fracture of the proximal or distal radius accounting for over 90% of all associated fractures. One study has demonstrated that of all patients with a carpal fracture only 7% sustain multiple carpal fractures, with almost half of these perilunate fracture–dislocations and over 90% involving a fracture to the scaphoid. Work from Edinburgh on dislocations has demonstrated that perilunate dislocations have an incidence of 0.5/10 population per year, occurring at a mean age of 26 years, and are frequently seen in males. Two studies have demonstrated that high-energy mechanisms are a risk factor for sustaining an associated injury following a fracture of the carpus. Open carpal fractures are noted to be rare with only one documented in a 15-year study of 2,386 open fractures. 

Mechanisms of Injury for Carpal Fractures and Dislocations

An injury to the carpus commonly occurs following a mechanism in which an axial compression force is applied to the wrist, commonly leading to hyperextension where the palmar ligaments undergo tension and the dorsal articulations are subject to shear stresses. Given this, the most common mode of injury is a fall on the outstretched hand when an individual straightens the arm for protection and the body mass and external forces are placed across the wrist joint. Less common mechanisms occur when a force is applied across the wrist when it is in palmar flexion. Most carpal instabilities, in particular perilunate dislocations, occur as a consequence of a high-energy injury, such as a fall from a height on the outstretched hand or a motor-vehicle accident. 

Signs and Symptoms of Carpal Fractures and Dislocations

Patients with an injury to the carpus will commonly have wrist pain as their primary presenting complaint. Clinical examination uses a combination of clinical signs along with special tests to help determine the diagnosis; however, pain, swelling, and ecchymosis around the region of the carpus may be present in the acute phase. A full examination of the contralateral wrist can often be helpful, particularly when assessing for instability. The most constant and dependable sign of carpal injury is well-localized tenderness,: 

• Anatomical snuffbox (ASB): scaphoid injury
• Distal to Lister’s tubercle: scapholunate and lunate injury
• Dorsal margin, fingerbreadth distal to the ulnar head: triquetral, lunotriquetral ligament, and triquetrohamate ligament injury

Changes in alignment of the hand, wrist, and forearm may be clinically evident on inspection of the extremity. Swelling over the proximal carpal row is suggestive of a ligament avulsion with or without an associated fracture. With carpal instability or dislocation, a gross deformity may be apparent, such as a marked prominence of the entire carpus dorsally which is suggestive of a perilunate dislocation. Compressive stresses applied actively or passively may produce pain at the site of damage and cause a palpable and audible snap, click, shift, catch, or clunk, which may also be appreciated with movement of the wrist. Stress loading the wrist with compression and motion from radial to ulnar deviation may simulate midcarpal instability (MCI) and produce a “catch-up clunk” as the proximal row of carpal bones snap from flexion to extension. It should be noted that tendon displacements with audible snaps are easily produced by some persons but are seldom symptomatic. Despite poor diagnostic performance characteristics due to the rarity of these injuries, the following special tests are proposed as aids to the diagnosis of carpal ligament injury: 

• Scaphoid shift test (Fig. 43-12)
  • Pressure applied over the scaphoid tubercle, wrist moving from radial to ulnar deviation
  • Positive if there is a “clunk” as the scaphoid subluxates dorsally out of the scaphoid fossa (up to 30% of normal wrists have positive result)
  • Diagnostic of scapholunate disruption
• Midcarpal shift test
  • Pressure applied over dorsum of the capitate, wrist moving from radial to ulnar deviation
  • Positive if there is a “clunk” as the lunate reduces from the palmarflexed position
  • Diagnostic of MCI
• Lunotriquetral ballottement
  • Lunate fixed with the thumb and index finger of one hand while the triquetrum is displaced palmarly and dorsally with the thumb of the other hand
  • Positive if painful
  • Diagnostic of lunotriquetral instability or arthritis
• Lunotriquetral shear test
  • Dorsally directed pressure to the pisiform (directly palmar to the triquetrum) and a palmarly directed pressure to the lunate (just distal to the palpable dorsoulnar corner of the distal radius)
  • Positive if results in reproducing the patient’s pain along with palpable crepitation or clicking
  • Diagnostic of lunotriquetral instability

The scaphoid shift test: pressure is applied to the palmar aspect of the scaphoid tubercle while moving the wrist from an ulnar to radial deviation.

Imaging and Other Diagnostic Studies for Carpal Fractures and Dislocations

Radiographs

The four standard views commonly employed in the assessment of scaphoid fractures can be used to detect most injuries to the carpus. These include neutral posteroanterior (PA) and lateral radiographs, along with a 45-degree radial oblique (supinated anteroposterior (AP) and a 45-degree ulnar oblique (pronated AP) views (Fig. 43-13). Additional extension and flexion views are advocated for detecting intercarpal ligament injury, along with a clenched-fist and stress views. Some authors also advocate contralateral wrist views because of the wide range of normal alignment. The standard neutral PA and lateral radiographs are useful for determining the presence of clear fractures and assessing carpal alignment, but are often poor for scaphoid fracture detection due to the tubercle overhang on the PA and the overlap on the lateral. The 45-degree radial oblique, 45-degree ulnar oblique, ulnar deviated AP, Ziter’s (Fig. 43-14), and carpal box or tunnel views are purported to improve the ability to diagnose a fracture, particularly of the scaphoid, and are discussed later. The VISI and DISI patterns of carpal malalignment are commonly detected using standard neutral lateral radiographs, with additional views in maximal radial and ulnar deviation if the diagnosis is in doubt. 

The four scaphoid views (PA, true lateral, radial oblique, ulnar oblique) detect most carpal fractures.

Ziter’s view is an additional image that can aid in the diagnosis of scaphoid fractures.

For the normal carpus with the wrist and hand in a neutral position, in the coronal (PA) plane a line drawn through the axis of rotation parallel with the anatomic axis of the forearm will pass through the head and base of the third metacarpal, the capitate, the radial aspect of the lunate, and the center of the lunate fossa of the radius. In the sagittal (lateral) plane with the wrist and hand in a neutral position, a line will pass through the longitudinal axis of the index finger metacarpal, capitate, lunate, and the radius, with the scaphoid lying on an axis at a 45-degree angle to this line. Standard radiographs should demonstrate a constant space between the scaphoid, lunate, and triquetrum, throughout the range of wrist motion. Knowledge of these facts can aid in the diagnosis of carpal fracture displacement, instability, and collapse: 

• Intercarpal, carpometacarpal, and radiocarpal joint spaces (neutral PA view)
  • Assessment of joint space between the individual carpal bones, carpal bones, and metacarpals, and the carpal bones and radius
  • Space is normally ≤2 mm, with ligament disruption suspected at >3 mm and often diagnostic at >5 mm
  • Clenched-fist views can accentuate the gap if equivocal
• Gilula’s lines (Fig. 43-15) (neutral PA view)
  • Arc 1 runs along the proximal articular surface of the proximal carpal row
  • Arc 2 runs along the distal articular surface of the proximal carpal row
  • Arc 3 runs along the proximal cortical margins of the capitate and hamate
  • Three carpal arcs that produce smooth curves when drawn, with a broken arc diagnostic of a fracture and/or instability, particularly perilunate fracture–dislocations
  • With lunotriquetral dissociation, an intercarpal gap may not be seen but a break in the normal carpal arc of the proximal carpal row is evident
   

  Figure 43-15

  Gilula’s lines.

  

  Figure 43-15

  Gilula’s lines.

  

  X
• Carpal height ratio = carpal height/length of third metacarpal (neutral PA view) (Fig. 43-16)
  • One method of measuring the carpal height is to measure the distance between the base of the third metacarpal to the subchondral sclerotic line of the articular surface of the distal radius. The line should bisect the middle of the radius and metacarpal.
  • Used to quantify carpal collapse with the normal ratio 50% (45% to 60%) and less than 45% indicative of carpal collapse
  • One study has suggested gender-specific normal values
  • Limited diagnostic value for carpal instability
  • Alternate method uses height of the capitate instead of the third metacarpal
   

  Figure 43-16

  Carpal-height ratio, which is calculated by L2/L1.

  

  Figure 43-16

  Carpal-height ratio, which is calculated by L2/L1.

  

  X
• Intercarpal and intracarpal angles (neutral lateral view) (see Table 43-4)
  • Scapholunate angle (normal 45 degrees, ranges from 30 to 60 degrees)
    • Angle created by the longitudinal axes of the scaphoid and the lunate (Fig. 43-17)
       

      Figure 43-17

      The scapholunate angle is created by the long axis of the scaphoid and a line perpendicular to the capitolunate joint.

      

      Figure 43-17

      The scapholunate angle is created by the long axis of the scaphoid and a line perpendicular to the capitolunate joint.

      

      X
    • Long axis of the scaphoid is a line tangential to the palmar convex surfaces of the proximal and distal poles of the scaphoid
    • Long axis of the lunate is a line perpendicular to the line connecting the dorsal and palmar lips of the lunate
    • DISI pattern greater than 60 degrees, VISI pattern when less than 30 degrees; greater than 80 degrees is diagnostic of carpal (scapholunate) instability
  • Capitolunate angle (normal <15 degrees): greater than 15 to 20 degrees is suggestive of carpal instability (see Fig. 43-9)
  • Radiolunate angle (normal <15 degrees): greater than 15 to 20 degrees is suggestive of carpal instability

Gilula’s lines. A: AP views show three smooth Gilula’s arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B: Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. Additional findings are the cortical ring sign produced by the cortical outline of the distal pole of the scaphoid and a trapezoidal shape of the lunate.

Carpal-height ratio, which is calculated by L2/L1.

The scapholunate angle is created by the long axis of the scaphoid and a line perpendicular to the capitolunate joint.

Secondary Imaging Methods

Secondary imaging modalities are predominantly used in the assessment of scaphoid fractures and the diagnosis of intercarpal ligament injury and any associated instability (Table 43-5). For carpal fractures, further imaging is used for diagnosis, determining displacement or in the assessment and management of malunions, nonunions, or bone loss. Detailed discussion of the use of secondary imaging modalities for fractures of the scaphoid is discussed in the scaphoid fracture section. 

The following are measures of scaphoid fracture displacement, primarily assessed on CT and/or MR imaging,: 

• Lateral intrascaphoid angle (normal 30 degrees ±5 degrees; sagittal view)
  • Angle created by lines drawn perpendicular to the proximal and distal articular surfaces/poles of the scaphoid (Fig. 43-18A)
     

    Figure 43-18

    

    Figure 43-18

    

    X
  • An angle greater than 35 degrees is used as a cut-off for displacement
• AP intrascaphoid angle (normal 40 degrees ± 5 degrees; coronal views)
  • Angle created by lines drawn perpendicular to the proximal and distal articular surfaces
• Dorsal cortical angle (normal 140 degrees, abnormal >160 degrees; sagittal view)
  • Angle created by tangential lines drawn along the dorsal cortices of the proximal and distal scaphoid fragments (Fig. 43-18B)
• Scaphoid height-to-length ratio (normal 0.60, abnormal >0.65; sagittal view)
  • Ratio of the lines measuring the height and length of the scaphoid
  • The length is determined by a palmar line drawn from the most proximal to the most distal edge of the scaphoid (Fig. 43-18C)
  • The height is the maximal point with a line perpendicular to the length line

A: Lateral intrascaphoid angle measurement. B: Dorsal cortical angle measurement. C: Scaphoid height-to-length ratio measurement.

Bain et al. determined the intra and interobserver reliability of the lateral intrascaphoid angle to be poor and poor to moderate, respectively, the dorsal cortical angle to be moderate to excellent for both, and the height-to-length ratio was excellent and moderate to excellent, respectively. 

A high index of suspicion is critical for these injuries as they can be missed in up to 25% of cases. Additional cost-effective tools to help in the diagnosis of these injuries can be performed with live/video fluoroscopic evaluation of the wrist, which can provide diagnostic clarity for dynamic instability. Sensitivities for this technique are reported between 86% and 95%, with similar specificity between 80% and 97% for diagnosing scapholunate ligament injury. Importantly, this technique provides an improved detection for low-grade injuries compared to static radiographs and has good reliability between and within observers. Other authors have advocated this technique in the detection of lunotriquetral and midcarpal injuries as well. 

Ultrasound scanning (USS) also provides an additional tool for the detection of these injuries. Boutry et al. and Lacelli et al. demonstrated the reproducibility and utility of US in the detection and visualization of the carpal ligaments. Subsequent studies have demonstrated the utility of this technique, although few comparative studies exist. The technique is also operator dependent and has yet to be universally adopted because of this. 

Carpal Injuries: Pearls and Pitfalls

• Standard scaphoid radiographic views detect most carpal injuries.
• DISI pattern is most commonly associated with displaced scaphoid fractures and SLD.
• Perilunate dislocations can be missed.
• Assessment of Gilula’s lines can aid in the diagnosis of perilunate dislocations.
• CT is useful in the diagnosis of suspected carpal fractures and assessment of union.
• MRI is useful in detecting suspected fractures and AVN of the carpus.
• Wrist arthroscopy can be used as an aid to the diagnosis of ligament injuries and fracture displacement.

Scaphoid Fractures

Introduction to Scaphoid Fractures

The name scaphoid comes from the Greek word skaphos meaning boat, a reference to the shape of the bone. Acute scaphoid fractures were first described by Cousin and Destot in 1889, with subsequent descriptions by Mouchet and Jeanne in 1919. The position of the scaphoid on the radial side of the wrist, as the proximal extension of the thumb ray, makes it vulnerable to injury. 

The scaphoid’s location, shape, and the surrounding anatomy can obscure our appreciation of fractures and challenge our assessment of healing. Some nondisplaced fractures of the scaphoid are not visible on radiographs taken at the time of injury (occult scaphoid fracture). Patients with radial-sided wrist pain and tenderness after a fall are often suspected of having an occult scaphoid fracture. The suspected scaphoid fracture remains a problematic clinical scenario despite advances in both knowledge and radiologic imaging. The mindset and thrust of research in recent years has been to aim to find the optimal radiologic test so that no fractures are missed, and to establish an early definitive diagnosis thus limiting immobilization, restrictions, and the number of further clinical assessments. However, despite advocates for the various secondary imaging modalities, a clear cost-effective answer to the problem has not emerged. The most recent US-based cost-effective analysis study suggested early MRI provides early diagnosis with a lower overall system cost compared to CT and repeat 2-week clinic assessment. 

Displaced, comminuted, and unstable fractures of the scaphoid are routinely managed with surgical intervention. Much of the current controversy surrounds the undisplaced or minimally displaced acute fractures. The current opinion is that patients with undisplaced fractures of the scaphoid need protection and cast immobilization until union (typically between 6 and 12 weeks), accounting for a loss of time and productivity in a predominantly young and active population. Advocates for early operative intervention claim that screw fixation not only limits the need for a cast but may also allow earlier return to sports and work. 

Pathoanatomy and Applied Anatomy Related to Scaphoid Fractures

The scaphoid bone is located in the proximal carpal row on the radial aspect of the wrist and is a small, irregular S-shaped tubular bone. It lies entirely within the wrist joint and is located at a 45-degree plane to the longitudinal and horizontal axis of the wrist. Articulations are with the trapezium/trapezoid (distal surface), radius (proximal/lateral surface), capitate (medial surface), and lunate (medial surface). 

The proximal articular surface is convex and articulates with the radius. The capitate head articulates with a sulcus on the scaphoid located across the radial articular surface and thus providing a socket-like fit for the capitate. The scaphoid gently pronates and flexes distally such that the distal pole sits ulnarly angulated relative to the proximal pole. At the distal articular surface, two distinct articular facets for the trapezium and trapezoid are present forming the STT joint. With a surface extensively covered with articular cartilage (over 80%), the scaphoid has a reduced capacity for periosteal healing and an increased tendency for delayed union and nonunion. 

The scaphoid is ridged across its nonarticular dorsoradial surface, along which the critical dorsal ridge vessels traverse. The ridge is the insertion point for both the dorsal component of the scapholunate and intercarpal ligaments (see Table 43-2). 

The ligamentous attachments of the scaphoid are predominantly found on the nonarticular dorsoradial surface.360, The short intrinsic ligaments provide stability to the scaphoid through attachments to the other carpal bones, in particular the lunate, and merge with the extrinsic ligaments and capsule of the wrist. The radioscaphocapitate ligament does not attach to the bone itself but crosses the waist, acting as a sling across it allowing it to rotate. There are no tendon attachments to the scaphoid. Through these articulations and soft tissue attachments the scaphoid acts as a midcarpal joint “bridge” linking and synchronizing the motions of the proximal and distal carpal rows as part of the key intercalated segment. Motion of the scaphoid includes rotation proximally and gliding distally, while providing stability to the midcarpal joint. 

The potential for nonunion of the scaphoid is often ascribed to the meagre, largely retrograde blood supply (see Table 43-3) through soft tissue attachments via two vascular pedicles originating from the scaphoid branches of the radial artery (Fig. 43-19): 

• Dorsal branch: Enters via the small foramina along the spiral groove and dorsal ridge of the scaphoid and supplies 70% to 80% of the scaphoid proximally, including the proximal pole
• Volar branch: Enters via the scaphoid tubercle and supplies the remaining 20% to 30% of distal scaphoid

The vascular supply of the scaphoid is provided by two vascular pedicles.

It should be noted that the waist of the scaphoid has been shown to have minimal or no perforating vasculature. Furthermore, no vessels perforate the proximal dorsal cartilaginous area or through the scapholunate ligament. Proximal fractures are inexorably associated with at least temporary disruption of the interosseous blood supply to the proximal pole. For the detailed pathoanatomy of injury, please see pages 1600-1601. 

Assessment of Scaphoid Fractures

Mechanisms of Injury of Scaphoid Fractures

Acute scaphoid fractures account for 2% to 3% of all fractures, approximately 10% of all hand fractures and between 60% and 80% of all carpal fractures. The incidence of scaphoid fractures quoted in the literature is inconsistent with a range from 1.5 to 121 fractures per 100,000 persons per year. It is most probable that the wide variation documented is due to the use of predominantly retrospective data, analysis of specific patient populations (e.g. military), as well as the limitation of many large datasets to distinguish between a true and suspected fracture. The lower quoted incidences appear to be more representative, given that the average incidence of fractures of the distal radius is 195 per 100,000 population per year. Data from Edinburgh documented the epidemiology of true radiographically confirmed acute fractures of the scaphoid in a defined adult population using a prospective dataset and found an annual incidence of 29 per 100,000 per year, which is consistent with previous studies from Scandinavia quoting an annual incidence of 26 to 39 per 100,000 per year. The mean age in the literature ranges from 25 to 35 years, with males significantly younger at the time of injury compared to females suggesting scaphoid fractures most closely fit a type B fracture distribution curve (see Fig. 43-11). A male predominance is seen with a male to female ratio of approximately 2.5:1. Two studies have documented male sex as a risk factor associated with a true fracture. 

Scaphoid fractures usually occur after a fall on to the outstretched hand or during sports with two studies reporting that sports injuries are associated with a true fracture. One study has documented that a low-energy fall from standing height has been shown to occur more frequently in females, with males more likely to sustain their fracture after a high-energy injury such as sports or a motor-vehicle collision. This is in keeping with the younger age at which fracture occurs in males. Sports noted to cause increased risk include football, basketball, cycling, and skateboarding, depending on the study origin. Fractures of the scaphoid are being increasingly documented after punching or assault-related injuries. 

An exact understanding of the epidemiology and etiology of fractures of the scaphoid is essential when considering the diagnosis of the suspected scaphoid fracture, in particular the use of further imaging modalities such as CT or MRI. Given the increasing evidence for earlier return to function following fixation of the scaphoid it is important to consider that the population affected is predominantly young and active, with these patients more frequently sustaining unstable injuries. 

Injuries Associated with Scaphoid Fractures

Associated injuries occur in approximately 10% of all scaphoid fractures, commonly following a high-energy mode of injury, and proximal radial fractures are most frequently seen. Fractures of the distal radius can occur, as can perilunate dislocations and transscaphoid perilunate fracture–dislocations. A concomitant fracture of the distal radius can be indicative of more serious ligamentous disruption and carpal instability. It is essential to consider that a radiograph never accurately exposes the true degree of joint and ligament damage. 

Studies have aimed to document the incidence of associated ligamentous injuries given the increased use of wrist arthroscopy in the management of scaphoid fractures. Caloia et al. documented an associated ligamentous and/or bony injury in 63% of the 24 acute scaphoid fractures in their series. In a more recent study of 41 scaphoid waist fractures, acute intrinsic ligament injuries were found in 34 cases, with 29 a scapholunate ligament injury (complete rupture in 10). Interestingly, there was no significant difference in the rate of ligament injury between nondisplaced and displaced scaphoid fractures. The clinical relevance of these associated ligamentous injuries is yet to be determined. 

Signs and Symptoms of Scaphoid Fractures

The diagnosis of a fracture to the scaphoid is made by a combination of clinical history, examination, and radiographic assessment. Patients classically present with wrist pain following a fall onto the outstretched hand, with almost 90% recalling a hyperextension injury. Clinical examination uses a combination of clinical signs (Table 43-6). Generally, pain, swelling, ecchymosis, and tenderness around the region of the scaphoid may be present in the acute phase. Standard four-view radiographs are subsequently used to confirm the diagnosis. 

However, up to 30% to 40% of scaphoid fractures are not identified on initial assessment and investigation with standard four-view radiographs and are thus classified as having a suspected fracture. Patients who are subsequently found to have a fracture confirmed on repeated assessment and radiologic imaging, most frequently at 10 to 14 days after injury, are said to have had an occult fracture of the scaphoid. In these cases, the treating surgeon must balance employing immobilization and restriction of activities in a predominantly young and active population against the risks of nonunion and arthrosis associated with an undiagnosed and untreated scaphoid fracture. 

Patients present with a history of hyperextension to the wrist, often following a fall, sports, or punch injury. It is important to determine a history of previous trauma to the scaphoid and not treat a nonunion as if it is an acute fracture. The main complaint is of radial-sided wrist pain, with localized tenderness over the scaphoid in the region of the ASB. 

No single sign has been found to be adequately sensitive or specific, with a recent meta-analysis by Mallee et al. confirming this with level-1 evidence (see Table 43-6). The first studies in this area analyzed the sensitivity and specificity of the classic individual clinical signs. ASB tenderness is oversensitive and has poor specificity. In a study of 246 patients with a suspected fracture of the scaphoid, ASB tenderness was found to have a sensitivity of 90% and a specificity of 40%, with scaphoid tubercle tenderness having a sensitivity of 87% and specificity of 57%. From another study that performed a prospective analysis of 73 patients with a suspected scaphoid fracture, the sensitivity and specificity of ASB pain on ulnar deviation of the pronated wrist was calculated. That individual sign had a negative predictive value (NPV) of 100% and the authors concluded that patients with a negative test could be safely discharged at presentation as they did not have a scaphoid fracture. 

Further studies aimed to improve the diagnostic performance characteristics, in particular the specificity of the clinical signs, by combining them. Parvizi et al. performed a prospective study of 215 consecutive patients and demonstrated that the use of one clinical sign in isolation was insufficient for the diagnosis of a fracture, but that a combination of ASB tenderness, scaphoid tubercle tenderness, and ASB pain on longitudinal compression of the thumb generated a sensitivity of 100% and a specificity of 74%. However, these findings were valid only for the first 24 hours after injury. 

More recent studies have examined alternative clinical signs as predictors of a fracture of the scaphoid. Unay et al. analyzed 10 clinical examination maneuvers on 41 patients with suspected scaphoid fractures and used MRI to determine the presence or absence of a fracture. They demonstrated that pain on thumb–index finger pinch and ASB pain on pronation of the forearm were most suggestive of a true scaphoid fracture. Duckworth et al. determined that the best predictors of fracture within 72 hours of injury were the absence of pain on ulnar deviation of the wrist and pain on thumb–index finger pinch, with scaphoid tubercle tenderness most predictive at week 2. Bergh et al. developed a clinical scaphoid score (CSS) using three clinical tests: tenderness in the ASB with the wrist in ulnar deviation (3 points), tenderness over the scaphoid tubercle (2 points), and pain upon longitudinal compression of the thumb (1 point). Using MRI as the reference standard, they identified 13 occult scaphoid fractures on MRI in 154 patients with normal radiographs and determined that patients with a CSS of 4 or higher require an MRI. Research in this area continues. 

Imaging and Other Diagnostic Studies for Scaphoid Fractures

Imaging

Neutral PA and lateral radiographic views are useful for ascertaining carpal alignment and the assessment of perilunate fracture–dislocations; however, they are poor at fracture detection, particularly with the tubercle overhang found on the neutral AP view. Views suggested to improve the ability to diagnose a scaphoid fracture are demonstrated in Table 43-7. 

Ziter’s view, or the “banana view,” uses an AP view of the wrist in ulnar deviation with 20-degree tube angulation to the elbow (see Fig. 43-14). This modified view can aid in the identification of scaphoid waist fractures, although fractures oblique to the beam are not well identified. Carpal box views have been shown to increase agreement in the interpretation of the standard four-view scaphoid radiographs from 36% to 55%, although they are not routinely utilized. Some authors also suggest comparative views of the contralateral uninjured wrist can aid in the diagnosis of the suspected fracture. 

Some studies have suggested that when clinical and radiographic assessment is carried out by experienced surgeons, all suspected scaphoid fractures can be detected within 6 weeks of injury. However, most of the literature consistently indicates that up to 30% to 40% of scaphoid fractures are not identified on initial assessment and investigation with four-view radiographs. Standard four-view scaphoid radiographs have been demonstrated to have low inter and intraobserver reliability for the diagnosis of suspected scaphoid fractures. Repeated radiologic assessment has been documented to have low sensitivity, with one study only detecting 50% of suspected scaphoid fractures. Barton suggested three possible reasons why standard scaphoid radiographs are often misinterpreted: 

• A dark line may be formed by the dorsal lip of the radius overlapping the scaphoid
• The presence of a white line formed by the proximal end of the scaphoid tuberosity
• The dorsal ridge of the scaphoid may appear bent on the semisupinated view

Tomosynthesis, an emerging technology that can generate cross-sectional images from standard radiographs, may be a useful tool in the future. This technique imparts low radiation doses and may prove helpful for occult injuries. In a recent study with a small sample size, digital tomography had a positive predictive value (PPV) of 100% and a sensitivity of 67%. Additional evaluation and feasibility studies are required before this technique can be utilized in day-to-day clinical practice. 

Soft tissue signs of a scaphoid fracture on plain radiographs include the scaphoid fat pad sign (distortion or loss of adjacent fat stripes over the radial aspect of the scaphoid on the PA view with the wrist in ulnar deviation) and the pronator fat pad/stripe sign (a prominent pronator quadratus fat pad over the volar aspect of the wrist on the lateral view). Although there are advocates for these soft tissue signs, most have demonstrated them to be unreliable detectors for the presence of a suspected scaphoid fracture. Given the difficulty with confidently diagnosing a scaphoid fracture on standard radiographs when clinical suspicion is present but radiographs are negative, immobilization is recommended with repeat examination and radiographs performed within 10 to 14 days of injury. The delay may lessen both tenderness and anxiety leading to a better examination. Although an established approach to diagnosis, the use of delayed repeat imaging is not without issue. Some authors argue that the interobserver agreement may remain low at time points 2 to 6 weeks after the index injury. 

US is a noninvasive and relatively inexpensive technique for diagnosing scaphoid fractures; however, it is operator dependent and has been shown to be least effective in detecting true fractures with a sensitivity ranging from 37% to 93% and a specificity ranging from 61% to 91%. There are advocates for the use of high–spatial-resolution sonography for detecting the suspected scaphoid fracture, with the sensitivity rising up to 100% and the specificity as high as 91%. Others have suggested it to be a useful precursor to further imaging modalities when used in the emergency department. 

There are strong advocates for bone scintigraphy; however, most authors think that the specificity is too low when compared to both CT and MRI. Beeres et al. analyzed 100 patients with a suspected fracture and found bone scintigraphy had a sensitivity of 100% and a specificity of 90%, concluding that there was no advantage to MRI over this modality. Further work from this group found similar results when comparing CT with bone scintigraphy. However, in 43 patients with suspected scaphoid fractures, Fowler et al. found that bone scintigraphy was inferior to MRI for both sensitivity and specificity, using 1-year follow-up as the reference standard. 

This was refuted recently by a meta-analysis suggesting scintigraphy was as sensitive and predictive in excluding fractures of the scaphoid when compared to MRI, although it was not as specific for the detection of a fracture. Timing of bone scintigraphy plays a key role in the ability of the test as a gold standard diagnostic aid, as the time from injury increases the sensitivity of the scan, with a reported 100% sensitivity at 96 hours. The most recent Cochrane review highlighted the potentially problematic overtreatment of patients with a positive bone scintigraphy, due to the lower specificity compared to CT and MRI. The somewhat invasive nature of the investigation further reduces the practicality of this modality. 

Many authors advocate the use of CT for diagnosing true fractures among suspected scaphoid fractures although some have cautioned against its use for undisplaced fractures. In an analysis of 47 patients with a suspected scaphoid fracture, using 2-week radiographs or MRI as the reference standard, CT was found to be 94.4% sensitive and 100% specific with a NPV of 96.8% and a PPV of 100%. CT has also been shown to be useful in detecting other injuries around the wrist, particularly in the acute assessment of the suspected fracture. In a study of 28 patients with a suspected scaphoid fracture who underwent CT, undisplaced fractures of the distal radius or carpus were demonstrated in 36% of patients. Stevenson et al. performed a retrospective analysis of 84 patients with suspected scaphoid fractures who underwent CT within 14 days of injury. A total of 54 scans were normal. Of the thirty abnormal scans the authors found that 7% were occult scaphoid fractures, 18% were occult carpal fractures (triquetrum, capitate, lunate), and 5% were distal radius fractures. Overall, approximately a third of CT scans for suspected scaphoid fracture found other wrist injuries. Ideal patient positioning may also be beneficial in optimizing the image quality and plane of the images. The long axis of the scaphoid can be positioned parallel to the scout beam from the CT gantry and this may help facilitate sagittal images. 

To determine the intra and interobserver reliability of CT for the diagnosis of undisplaced scaphoid fractures, one study used eight observers to evaluate CT scans from 30 patients. Although they found substantial intra and interobserver reliability, they also noted a high false-positive rate, possibly from the misinterpretation of vascular channels as a unicortical fracture (Fig. 43-20). A very recent study has reported a kappa value of only 0.51 (moderate agreement) for the interobserver reliability among radiologists when using CT for the diagnosis of scaphoid fractures. However, a more recent study evaluating the utility of cone-beam CT reported a kappa value of 0.95. 

Sagittal CT slice demonstrating an undisplaced fracture of the scaphoid waist, although this could be mistaken for a vascular channel.

For the suspected scaphoid fracture, MRI is argued to be the best investigation, although some institutions have limited access and there are inconsistencies regarding cost efficiency. In a prospective blind study in which MRI scans were performed within 72 hours of injury in 32 patients with a suspected scaphoid fracture, it was found that the sensitivity and specificity of MRI were 100%, with potential savings of $7,200 per 100,000 of the population through avoiding unnecessary immobilization and review. This study used clinical and/or radiographic follow-up at 6 weeks as the reference standard. 

Karl et al. used cost data from previously published clinical trials to generate a decision analysis model. Three diagnostic strategies were compared: empiric casting and orthopedic follow-up at 2 weeks, immediate CT evaluation, and immediate MRI evaluation. The authors found a significant cost benefit to both advanced imaging strategies compared with standardized empiric treatment. Significant changes in both cost (more than $2,000 increase with MRI/CT) and sensitivity (decreased to 25% for CT and 32% for MRI) were required to balance the cost-effectiveness of these advanced modalities. In contrast, two randomized controlled trials of patients with a suspected scaphoid fracture compared early MRI and discharge if no injury to standard reassessment in clinic 10 to 14 days after injury. Both studies found no difference in total direct or indirect medical costs. However, the studies did find conflicting results in terms of patient satisfaction, number of sick days and time in immobilization. The answer regarding the overall utility and cost effectiveness of MRI remains unclear. 

Although MRI is the most successful secondary imaging modality to date in terms of performance characteristics, in low prevalence situations the PPV has been found to be only 88% and recent work has documented the potential for false-positive MRI scans. Ring et al. performed an analysis to determine the diagnostic performance characteristics of the various secondary imaging modalities utilized in the assessment of the suspected scaphoid fracture (Table 43-8). Using Bayesian formulae and an average published prevalence of scaphoid fractures among suspected fractures of 7%, the NPV for MRI was 88%, meaning that around 12% of patients with a suspected scaphoid fracture undergo an MRI that is interpreted as demonstrating a fracture when they may not actually have a fracture. A recent analysis of MRI scans in healthy individuals also highlighted the potential for false-positive MRI scans, with benign abnormalities diagnosed as fractures by numerous blinded radiologists. This study concluded that MRI is not a suitable reference standard for true scaphoid fractures amongst patients with suspected fractures. 

A prospective cohort study that again used 6-week radiographs as the reference standard demonstrated that CT and MRI had comparable diagnostic performance characteristics for detecting true fractures among suspected scaphoid fractures, with the PPV for CT being 76% compared to 54% for MRI. This study also questioned whether or not bone edema on MRI and small unicortical lines on CT are diagnostic of a true scaphoid fracture. The rate of scaphoid bone bruising (Fig. 43-21) on MRI leading to occult fracture has been documented to be 2% in one study. 

MRI demonstrating scaphoid bone bruising but no fracture.

Current Practice

Despite many advocates, the optimal imaging modality is not known. Yin et al. presented a meta-analysis of 26 studies to determine the prevalence adjusted diagnostic performance characteristics of bone scintigraphy, CT, and MRI for suspected scaphoid fractures. Of the 26 studies, 9 used 6-week radiographic follow-up as their reference standard. Bone scintigraphy and MRI were shown to have comparable high sensitivity rates, though MRI was more specific. Mallee et al. have since carried out a Cochrane review of five studies to determine the diagnostic performance characteristics of MRI for suspected fractures of the scaphoid and found a sensitivity of 88% and a specificity of 100% (Table 43-9). 

National guidelines of some professional associations, as well as advocates for MRI, suggest an overly optimistic assessment for its use. The Royal College of Radiologists (UK) recommends that on current evidence bone scintigraphy, CT and MRI are comparable for triaging the suspected acute scaphoid fracture. However, the American College of Radiology (ACR) concludes radiographs and MRI should be utilized. An international survey of 105 hospitals worldwide was performed to determine their own imaging protocol for the suspected scaphoid fracture and reported a high rate of inconsistency amongst the hospitals with only 22% found to have a fixed protocol. 

A more recent survey of English hospitals carried out by Smith et al. collected survey responses from 116 hospitals (82% response rate) and found repeat radiographs were used in 68% of hospitals prior to second line imaging, which included MRI (63.9%), CT (27%) or isotope bone scan (9%). They also reported that secondary imaging was carried out between 10 days and 4 weeks following the initial injury in 86.8% of hospital trusts. 

There are currently two large-scale randomized trials ongoing to evaluate both the cost-effectiveness of immediate advanced imaging studies (SMaRT Trial [UK] and an Australian Group). Additional information from these studies hopefully will help guide clinical decision making. 

Given the combination of oversensitive clinical signs and no consensus gold standard for diagnosing a scaphoid fracture, most patients with a suspected fracture of the scaphoid receive more protection and diagnostic testing than is required. This can lead to issues with wrist stiffness and costs to both the health care system and the patient with time off work and sports in a predominantly young, healthy, and active patient group. 

It has been proposed that the assessment of the various diagnostic tests for the assessment of the suspected scaphoid fracture must account for two important issues. The first is the low prevalence of true fractures amongst suspected fractures, which greatly lowers the probability that a positive test will correspond with a true fracture as false positives are nearly as common as true positives. Research has documented that between 5% and 20% of patients who attend the emergency department with a suspected scaphoid fracture are ultimately found to have a true fracture. Given that false positives and false negatives are 5% to 10% for most diagnostic tests, this low prevalence of disease among assessed patients leads to low PPVs according to Bayes’ theorem even when the diagnostic test is both highly sensitive and specific (Fig. 43-22). 

The relationship between fracture prevalence and the positive predictive value of diagnostic tests, in this case, CT.

The second issue relates to the fact that the calculation of the diagnostic performance characteristics (sensitivity, specificity, PPVs and NPVs, and accuracy) for the various imaging modalities using a traditional formula requires a consensus reference standard for the presence or absence of a fracture. The most frequently used standard in the literature is the absence of a fracture on radiographs at 6 weeks after injury which more recently has been found to have questionable accuracy. However, given the lack of consensus, an alternative method for calculating diagnostic performance characteristics based on a statistical method that identifies clinical factors that tend to associate (latent classes) in patients with a high probability of fracture is preferable. This technique has been applied to the diagnosis of carpal tunnel syndrome, as well as in two recently published studies on the assessment of the suspected scaphoid fracture. These studies found small but potentially important differences between the results obtained using traditional formula and those obtained using latent class analysis. 

The upshot of the issues raised by the low prevalence and lack of consensus reference standard is that there will likely always be a small probability of missing a true fracture among the suspected scaphoid fracture. If patients, doctors, and society can accept an approximate 1% chance of missing a true fracture, we may have adequate management strategies at the current time. It is not clear that imaging technology will improve these odds because better imaging has findings that are difficult to interpret. The best option might be to increase the pretest odds of a fracture prior to ordering advanced imaging, and this can be done by applying a clinical prediction rule to determine when to order advanced imaging. 

The benefit of clinical prediction rules in medicine to guide, but not dictate, management of patients is well documented. It has been suggested that an important step to improving the diagnostic performance characteristics of the various imaging modalities for the suspected scaphoid fracture would be to increase the prevalence of the true scaphoid fracture amongst suspected fractures through the development and promotion of clinical prediction rules. These rules would incorporate a combination of demographic and clinical risk factors predictive of a true scaphoid fracture. Implementation of these rules could potentially increase the prevalence of true scaphoid fractures among suspected fractures and subsequently allow the utilization of sophisticated secondary imaging in high-risk patients, potentially leading to improved diagnostic performance characteristics of diagnostic imaging. 

Two studies have demonstrated the potential of clinical prediction rules to improve the management of suspected scaphoid fractures. One study from Holland analyzed 78 patients with a suspected scaphoid fracture and determined using multivariate analysis that a reduction in extension of greater than 50%, supination strength of up to 10%, and the presence of a previous fracture were most predictive of a true fracture. A recent prospective study from Edinburgh and Boston analyzed 223 patients with a clinically suspected or radiographically confirmed scaphoid fracture, using radiologic imaging at 6 weeks as their reference standard. They demonstrated that risk factors for a true fracture were male gender, sports injury, ASB pain on ulnar deviation of the wrist, and pain on thumb–index finger pinch at presentation, as well as persistent scaphoid tubercle tenderness at 2-week review. They incorporated these signs to develop clinical prediction rules that can guide assessment of these patients (Fig. 43-23). Ultimately, this study demonstrated that clinical prediction rules have a substantial and meaningful influence on the probability of a suspected scaphoid fracture 

A potential management algorithm for suspected scaphoid fractures based on a clinical prediction rule developed by Duckworth et al. (Reprinted with permission from Duckworth AD, Buijze GA, Moran M, et al. Predictors of fracture following suspected injury to the scaphoid. J Bone Joint Surg Br. 2012;94:961–968.)

Classification of Scaphoid Fractures

There are several classification systems available for fractures of the scaphoid, including: 

• Russe classification
• AO classification
• Herbert and Fisher classification
• Mayo classification

The Russe classification predicts instability according to the inclination of the fracture line, for example, vertical oblique fractures. The AO classification breaks the fracture down into simple anatomic location (distal pole, waist, proximal pole) and comminution. 

Herbert and Fisher proposed a classification intended to identify those fractures most applicable for operative fixation and is commonly used throughout the literature (Table 43-10; Fig. 43-24). Type A fractures are stable fractures that often appear incomplete (unicortical), are associated with good union rates, and minimal treatment is required. Type B fractures include any acute bicortical fracture and are defined as unstable and hence will most likely require surgery due to displacement in plaster and delayed union being common. There are now two studies that have demonstrated that displaced waist of scaphoid fractures (Herbert B2) account for over a third of all fractures with one of these studies demonstrating that unstable Herbert type-B injuries were significantly more common in younger patients following a high-energy injury. Type C and D fractures are associated with delayed and nonunion, respectively. Characteristics of type C delayed union are defined as widening of the fracture line, development of cysts adjacent to the fracture, and relative density of the proximal fragment. 

Schematic drawing of Herbert and Fisher classification of scaphoid fractures.

Some argue the most useful classification for guiding treatment, particularly for displaced fractures, is the Mayo classification. The criteria for instability they set out are: 

• More than 1 mm of fracture displacement
• A lateral intrascaphoid angle greater than 35 degrees (see below)
• Bone loss or comminution
• Fracture malalignment
• Proximal pole fractures
• DISI deformity
• Perilunate fracture–dislocation

A criticism of all these classifications is that they do not clearly consider the extent of associated soft tissue injuries. 

Diagnosis of Displacement and Instability

Assessment of scaphoid fracture displacement and instability is essential, given the higher rates of nonunion associated with nonoperative management. All displaced fractures are unstable. A very small percentage of patients have a nondisplaced fracture (no radiologic signs of displacement) but are unstable (fracture fragments move easily with probing or external pressure on the distal pole of the scaphoid during wrist arthroscopy). There are various methods for determining scaphoid fracture displacement (Table 43-11). As with the assessment of the suspected scaphoid fracture, the various imaging modalities are hindered by the low prevalence of displaced scaphoid fractures among all fractures. This leads to all modalities being better at excluding displacement rather confirming it. 

Standard scaphoid radiographs can be used to determine displacement in terms of translation, step-off, gap, rotation, and angulation (Fig. 43-25); however, some question the validity of their use with only moderate interobserver reliability being reported. Some authorities advocate the use of wrist motion views to demonstrate displacement, with the length of the scaphoid determined by comparing ulnar and radial deviation views in both wrists. Assuming that the two views are identical, any difference in length is indicative of a scaphoid deformity as a consequence of either a fracture and/or ligament injury. When displacement and instability is suspected, careful assessment of the lateral radiograph for the position of the lunate (see Fig. 43-17) and intrascaphoid angulation (see Fig. 43-18) is essential with repeat radiographs recommended as displacement may occur over time. 

A displaced and comminuted fracture through the waist of the right scaphoid.

CT is more accurate and reliable than radiographs for the diagnosis of scaphoid fracture displacement but it is unclear whether routine CT scanning improves outcomes. One study determined that CT had a low sensitivity in the diagnosis of radial/ulnar scaphoid displacement, while radiographs had a low sensitivity in the diagnosis of volar/dorsal displacement. Useful measurements include: 

• Fracture displacement
  • Step ≥1 mm at dorsal or radial cortices
  • Gap ≥1 mm (sagittal or coronal views)

The identification of displacement remains an important predictor of an increased risk of nonunion. Translation greater than 1 mm has been found to significantly increase the nonunion risk, with one series reporting an odds ratio for the risk of nonunion of 3.4, with a gap at the fracture site of greater than 3 mm giving an odds ratio of 9.9. 

Lozano-Calderon et al. analyzed the diagnostic performance characteristic of radiographs and/or CT for detecting the displacement of acute scaphoid fractures. They concluded that CT improved the reliability of detecting scaphoid fracture displacement but with an accuracy still less than 80% with the utilization of CT limited by the low prevalence of displaced fractures. One study found that quantitative measurements of scaphoid displacement using CT had limited intra and interobserver reliability, and others have suggested that measurement is influenced by the image plane and the thickness of the slices used. However, one recent study has suggested that training can lead to a slight increase in reliability for detection of displacement using such methods. 

Alternate methods of determining fracture displacement include USS, MRI, and wrist arthroscopy. Two studies demonstrated the utility of MRI for the characterization of scaphoid fracture displacement. Kappa values of 0.74 for sagittal displacement and 0.44 for coronal translation were noted by Bhat et al. They also reported that when compared to plain radiographic assessment alone, only 33% of those identified as displaced on MRI were detected by plain radiographs. One study has reported 100% specificity for determining scaphoid fracture instability when using USS; however, this is noted to be very user dependent. A recent study analyzed 58 consecutive patients with a scaphoid fracture who underwent arthroscopy-assisted operative fracture fixation. They found a significant correlation between radiographic comminution (more than two fragments) and arthroscopically determined displacement and instability. Using arthroscopy as the reference standard (Fig. 43-26), one study has found that radiographs and CT cannot be relied on to accurately diagnose scaphoid fracture displacement and/or instability. This study was novel in making a clear distinction between displacement and instability, noting a few radiologically well-aligned fractures that were unstable on arthroscopic visualization. To our knowledge, there are no data regarding the prognosis of well-aligned unstable fractures. 

Arthroscopic diagnosis of scaphoid fracture displacement.

Treatment Options for Scaphoid Fractures

Nonoperative Treatment of Scaphoid Fractures

Indications/Contraindications

Nonoperative Treatment of Scaphoid Fractures: Indications and Contraindications

Techniques

Early diagnosis is important for suspected fractures, distal pole/tubercle fractures, and undisplaced waist fractures. If the diagnosis is confirmed at the time of injury following the use of secondary imaging, for example, CT or MRI, the patient is treated as an undisplaced scaphoid fracture. This is usually with a simple below-elbow forearm cast with or without thumb immobilization for 6 weeks, with check scaphoid radiograph views or repeat CT scan obtained at the time of cast removal. When there are persistent clinical and radiologic signs of a fracture, further immobilization in a cast for an additional 2 weeks is recommended. When secondary imaging is not used at presentation, repeated assessment and radiologic imaging, most frequently at 10 to 14 days after injury, is usually performed. In the interim, a below-elbow forearm cast with (scaphoid cast) or without (Colles’ cast) thumb immobilization should be applied until the diagnosis is confirmed or refuted. 

Nonoperative management is routinely employed for scaphoid tubercle fractures (Herbert A1). Scaphoid tubercle fractures are a generally benign avulsion injury. Although some authors suggest that splinting is adequate, others prefer cast immobilization for 4 weeks. Tubercle fractures managed with casting can have radiographs that show persistent displacement and fibrous union causing no disability, although these findings are more commonly seen in fractures treated without immobilization. 

For nondisplaced, minimally displaced, or selected displaced fractures (see below), a below-elbow forearm cast with or without thumb immobilization can be used for 2 weeks. Clinical review is recommended with further scaphoid radiograph views mandatory, since surgery may be necessary if the fracture has displaced. When in doubt, further imaging is recommended. If the fracture remains undisplaced, a cast can be reapplied until fracture union is confirmed clinically and radiographically. There is a general consensus that most stable scaphoid fractures unite in 6 to 8 weeks with cast immobilization. However, examination and radiographs are unreliable so duration of immobilization is based ultimately on surgeon preference. Recent literature utilizing CT-based techniques has suggested that shorter immobilization periods of 4 to 10 weeks may result in union rates between 90% and 99.4%. 

One of the important questions regarding the nonoperative management of scaphoid fractures is the type of cast to be applied—an above-elbow cast, a Colles’ cast (below elbow without thumb immobilization), or a scaphoid cast. Three recent systematic reviews have concluded that on current evidence there is no advantage to any of these methods. Although some authors still advocate the use of above-elbow casts, two randomized studies have demonstrated no significant advantage in the use of above-elbow casts. In a further nonrandomized prospective study it was found that using an above-elbow cast may cause increased movement at the fracture site. 

The remaining debate is whether to use a scaphoid or a Colles’/below-elbow cast. Prior to 1942, Bohler proposed the use of an unpadded dorsal backslab, but then changed the cast to include the proximal phalanx of the thumb—the scaphoid cast. Since then, there have been several studies demonstrating no difference between the two techniques. In one cadaveric study it was found that provided the wrist was not in ulnar deviation, the position of the thumb had no influence on the fracture gap. Hambidge et al. randomly allocated 121 acute scaphoid fractures for conservative treatment in a Colles’ cast with the wrist immobilized in either 20 degrees flexion (n = 58) or 20 degrees extension (n = 63). They found no difference between groups in terms of union rates, wrist flexion, or grip strength but did find that the wrists which had been immobilized in flexion had a greater reduction in wrist extension. A recent biomechanical study contradicted these previous findings, reporting that despite wrist immobilization, active contraction of the finger tendons during grip can generate torque and forces on the scaphoid and may affect fracture strain. 

There are now two large prospective randomized trials comparing a below-elbow and scaphoid cast for an acute fracture of the scaphoid, with both having demonstrated no advantage to either method. For this reason, the use of below-elbow or forearm casts, rather than scaphoid casts, is advocated. 

Operative Treatment of Scaphoid Fractures

Indications

Controversy exists regarding the management techniques for nondisplaced or minimally displaced waist fractures (Herbert A2, B1, and B2). Studies in this area often include both nondisplaced and so-called minimally displaced fractures. Nondisplaced scaphoid fractures are usually stable, although there is no gold standard for confirming this, and achieve union rates between 95% and 99% when managed conservatively. Some authors suggest that cast immobilization is the method of choice for the primary treatment for undisplaced or minimally displaced fractures of the scaphoid. Variable rates (3% to 20%) of subsequent displacement in cast are reported due to a lack of consensus regarding the appropriate imaging modality to use and the criteria for displacement. 

Conflicting evidence exists to guide the optimal management of these injuries. There is a body of evidence to support the use of early percutaneous screw fixation of these fractures in some patients. Advocates of this approach cite a minimally invasive technique associated with a low complication rate, a shorter time to union by over a month, a more rapid improvement in functional testing, as well as an earlier return to sports and work, all in a predominantly young and active population. The shorter time to union is difficult to assess given radiographs are known to be unreliable. 

In evaluating these studies, it is important to note that patient occupation was a primary determinant of a faster return to work. Manual laborers have a clear advantage with return to work after surgical fixation as compared to nonmanual laborers. Some authors report a return to work rate of 40% in patients in a cast. Diaz et al. demonstrated no difference in time to return to work or long-term functional outcomes comparing open reduction internal fixation (ORIF) fixation to cast treatment. Clementson et al. reported an increased rate of union evaluated by CT scan in scaphoid waist fractures treated with cast immobilization (90%) as compared with arthroscopy-assisted screw fixation (82%). 

Herbert and Fisher reported an overall incidence of nonunion after conservative treatment at 50% and subsequently advocated the use of internal fixation for scaphoid fractures with a newly designed screw. More recently, there have been several studies advocating the use of early fixation for nondisplaced or minimally displaced fractures of the scaphoid with several randomized controlled trials now directly comparing the two treatment modalities (Table 43-12). 

McQueen et al. in their prospective randomized trial of 60 patients (30 percutaneous fixation, 30 cast) followed up for 1 year reported a significantly decreased time to union with a more rapid return of function, sports, and full-time work when compared with those managed conservatively. Low complication rates were also reported with the surgical technique. Arora et al. found similar results in their prospective study of percutaneous fixation with comparable costs for both techniques; however, Davis et al. reported cost savings of almost $6,000 in favor of surgical fixation. 

Saeden et al. performed a long-term prospective randomized 12-year follow-up study comparing ORIF and nonoperative management and found an earlier return to function in the operative group, recommending surgery be offered to young and active patients. This study did report an increased rate of radiologic signs of scaphotrapezial joint arthritis in the operative group, but did not correlate with subjective clinical findings. Dias et al. randomized 88 patients (44 ORIF, 44 cast) and followed them for 1 year after injury. They reported superior earlier results in the operative group across many of the outcome measures. There were 10 (23%) patients in the conservative arm that developed nonunion compared to none in the operative group. There was a 30% complication rate in the operative group, but all were minor, with most related to the scar due to the open technique. Despite these findings, the authors concluded that undisplaced or minimally displaced scaphoid waist fractures should be managed in a cast. 

Five of six systematic reviews with meta-analysis have concluded that on current evidence neither method is clearly superior. Surgical management is associated with improved functional outcome, a more rapid return to function, sports and work, and superior union rates, but also with a significantly higher rate of complications. However, these reviews included “minimally displaced” fractures and combined ORIF and percutaneous fixation under one umbrella for surgical management, with ORIF more commonly associated with complications. Alnaeem et al. recently reported on the complications in 171 operatively treated patients demonstrating a high rate of complications such as eccentric or protruding screws, screw migration, nonunion, AVN, and persistent pain. Throughout the literature, reports vary in the incidence and type of complications reported, but rates as high as 30% are found. Nonoperative treatment can be successful while avoiding the complications of surgery; however, patient-centric treatment should dictate treatment especially when either treatment can result in satisfactory outcomes. The results of the UK multicenter Scaphoid Waist Internal Fixation for Fractures Trial (SWIFFT) are eagerly anticipated. 

Surgical treatment is routinely employed for displaced scaphoid fractures (Herbert B1, B2), comminuted fractures (Herbert B5) and fractures associated with carpal instability and/or a dislocation (Herbert B4). Unstable or displaced fractures of the scaphoid, as well as proximal pole fractures, have an increased rate of redisplacement, delayed union, and nonunion when managed with cast immobilization alone. A recent systematic review of displaced scaphoid fractures found a four times greater risk of nonunion when compared with undisplaced fractures following conservative management, with nonunion 17 times more likely if a displaced fracture of the scaphoid is managed nonoperatively. 

It is debatable whether some displaced unstable scaphoid fractures can be treated in a cast. Since displacement is the primary and only evidence-based risk factor for nonunion, displaced fractures should be strongly considered for either open or arthroscopy-assisted reduction plus internal fixation. Some patients may not be suitable for an operation, including noncompliant patients and elderly patients with or without significant medical comorbidities. The consequence of managing these patients nonoperatively is not completely clear and it may be that in the elderly patient nonoperative management provides a comparable outcome to operative treatment, without the risks associated with surgery. Rates of redisplacement range from 12% to 22% union 70% to 90% and the development of osteoarthritis 16% to 31%. 

Percutaneous Fixation of Nondisplaced or Minimally Displaced Scaphoid Fractures

For undisplaced or minimally displaced fractures, percutaneous fixation is superior to ORIF providing superior union rates, faster functional recovery, and reduced surgical morbidity (e.g. scar, complex regional pain syndrome). Percutaneous fixation is a simple technique and can be performed through either a volar or dorsal approach, with neither reported to provide a superior outcome. 

Some think it is easier to get the screw in the center of the scaphoid using the dorsal approach, particularly for fractures of the proximal pole. The dorsal approach is often described using a small open incision citing an increased risk to tendons or nerves, in particular the posterior interosseous nerve, extensor digitorum communis to the index finger, and extensor indicis proprius, but we and other advocates such as Slade use a fully percutaneous approach. Slade placed the wrist in a traction tower to facilitate arthroscopy and used a mini image intensifier placed laterally. We place the mini C-arm vertically and stack a towel on the collector to keep the wrist bent with the carpus perpendicular to the beam. Slade and Geissler found the starting point for the screw through the arthroscope and suggested marking the spot with a large-gauge needle that could be used as a guide for wire insertion. We find the starting point under the image intensifier. Slade advanced the guidewires out of the volar surface of the thumb to get the wire out of the wrist, facilitating a PA view of the wrist without risking bending the wire. The wrist is bent at least 45 degrees to avoid bending the wire and takes radiographs perpendicular to the scaphoid rather than the distal radius. Slade placed the scaphoid in the image intensifier with some wrist flexion and enough rotation so that the distal and proximal poles of the scaphoid overlap creating a near-circular image in which the guidewire for the screw should be dead central. We find that view unpredictable and unreliable and use real-time 360-degree imaging to judge the position of the screw, again, keeping the wrist flexed. 

With the volar approach (Fig. 43-27), a potential disadvantage is an increased prevalence of later scaphotrapezial osteoarthrosis; however, this is commonly asymptomatic and appears to have no impact on the final outcome. For the volar approach, we placed the hand on a radiolucent table or with care directly on the collector of a small image intensifier with the shoulder abducted and the forearm in supination. The wrist is extended over a roll. The correct placement of the guidewire is crucial to the success of the procedure. It helps to remember that the scaphoid lies in a 45-degree plane to both the longitudinal and horizontal axes of the wrist. The incision point for the volar approach is found approximately 1 cm distal and radial to the scaphoid tubercle with the entry point on the scaphoid tubercle. A 4- to 5-mm skin incision is made or the guidewire can be inserted percutaneously and an incision made around the wire just large enough for the screw to pass once the wire position is acceptable. In a few cases with an overhanging trapezium, it may be necessary to insert the guidewire through the trapezium, which does not seem to result in added morbidity. The tip of the guidewire is placed on the scaphoid tubercle. The optimal entry point is one that will allow central placement of the screw in the proximal pole of the scaphoid. For the volar approach, this is often relatively radial on the distal pole. The guidewire is inserted at a 45-degree angle in both planes (roughly in line with the radially and palmarly abducted thumb metacarpal) aiming the tip at the apex of the proximal pole. The image intensifier is used to check wire placement using anteroposterior, lateral, and both supinated and pronated oblique views. 

Percutaneous stabilization of scaphoid fracture. A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4- to 5-mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping, variable-pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.

Percutaneous stabilization of scaphoid fracture. A: A fracture through the waist of the scaphoid. B: The wrist should be dorsiflexed prior to insertion of the K-wire and a 4- to 5-mm incision is made in the skin crease, sufficient for the insertion of the screw. C: The K-wire is inserted at a 45-degree angle in both planes and the position is checked using fluoroscopy. D, E: A second K-wire can be used if the position of the first wire is not quite adequate, or if there is concern regarding potential rotation of the fracture fragments. F: Insertion of the self-drilling, self-tapping, variable-pitch scaphoid screw using fluoroscopy to avoid rotation of fracture fragments. G: Postoperative views demonstrate good compression of the fragments and satisfactory position of the screw on all views.

Percutaneous Fixation of Nondisplaced or Minimally Displaced Scaphoid Fractures: Key Surgical Steps

When the wire is in an appropriate position in the scaphoid (and the alignment of the scaphoid is confirmed for displaced fractures), an attempt is made to measure the screw. The length of the screw should be measured carefully, and several millimeters subtracted from the measured length to avoid prominence at either end. It is useful to estimate the length of the scaphoid based on the preoperative measurement. Through a percutaneous insertion (incision just large enough to pass the screw), measurement can be difficult using the sleeve measure, but one can use a second wire of the same length and measure the difference. Some then drill the guidewire into the trapezium to anchor it. Predrilling is used depending on the type of screw. The drill is passed over the wire, stopping if there is any resistance as this may indicate a bend in the wire that will lead to drill or wire breakage. Even if the screw is self-drilling there is a risk of distraction of the fracture and so if predrilling is not used the progress of the screw should be monitored using image intensification to ensure that no rotation or distraction occurs at the fracture site. If distraction occurs, the screw is removed, and the track drilled. If there is a bend, the wire can usually be further advanced so that the drill passes over a nonbent part of the wire. After drilling the screw is advanced under image intensification. It is important to judge the screw length prior to fully seating the screw. The wire is then removed, and central positioning of the screw without joint penetration at the radiocarpal joint or prominence at the scaphotrapezial joint should be confirmed with AP, lateral, supinated, and pronated views of the wrist. 

There are a number of screws available which vary in size and pitch variation and can be partially, fully, or tip threaded, and with or without ancillary techniques for achieving compression (e.g. special screwdrivers or even mobile parts of the screw). Biomechanical studies support the common sense view that larger screws are stronger; however, there is no evidence that the type of screw affects the outcome with the exception that cannulated screws have been shown to improve central placement of the screw when compared with the Herbert screw. 

Open Reduction and Internal Fixation of Unstable or Displaced Scaphoid Fractures

Open Reduction and Internal Fixation of Unstable or Displaced Scaphoid Fractures: Key Surgical Steps

• A dorsal or volar approach may be used depending on the fracture location, displacement, and surgeon familiarity
• Temporary joystick K-wires are placed into the fragments to facilitate reduction
• Additional reduction aids include radial deviation and wrist extension, or scaphocapitate temporary K-wire fixation can be used
• Reduction is held with K-wire inserted through the incision or percutaneously
• A centrally placed compression screw may be placed as described for percutaneous fixation or scaphoid ORIF with a plate can be performed

McLaughlin was the first to report the use of primary ORIF for fractures of the scaphoid, and subsequently positive results have been reported in many studies. Displaced fractures are treated with either ORIF or arthroscopy-assisted percutaneous fixation. There must be direct visualization of fracture reduction as the strange shape of the scaphoid and complex carpal anatomy makes image intensification inadequate. Some fractures reduce with radial deviation and extension, but many require direct manipulation, which can be facilitated by the use of K-wires inserted into each fracture fragment. Both dorsal and volar approaches have been reported with success, with the palmar exposure limiting potential damage to the vascular supply, but the dorsal approach providing improved access to proximal fractures. Once the fracture is reduced, screw placement is as described for percutaneous fixation. 

For the volar approach, most use an incision across the transverse wrist creases in line with the flexor carpi radialis tendon. The incision starts distal to the distal pole of the scaphoid and is about 5 cm in length. The FCR tendon sheath is opened and the tendon is retracted in an ulnar direction. The superficial radial artery is either retracted distally or ligated. The wrist capsule is isolated and divided in line with the scaphoid, starting at the distal pole and ending as soon as the fracture is visualized, preserving as much of the radioscaphocapitate ligament as possible. The fracture is aligned and provisionally secured with a wire. Usually a volar screw is inserted as described above, but it is also possible to put in a dorsal screw percutaneously at this point. 

Arthroscopy-Assisted Reduction and Fixation of Unstable and/or Displaced Scaphoid Fractures

Some authors advocate arthroscopy-assisted reduction and fixation, with high union rates reported and the added advantage of being able to assess for the presence of associated soft tissue injuries. However, disadvantages are similar to that with the open technique and include a steep learning curve, extensor tendon damage, poor fracture reduction, nerve injury, and scaphotrapezial or radioscaphoid joint damage. Ultimately, it is not clear that arthroscopy-assisted surgery has any advantages over the open technique and might be more difficult and time consuming. Once the fracture is reduced, care must be taken not to flex, distract, translate, or rotate the fragments when inserting the screw and gaining compression. 

For this technique, the fracture is best seen through a midcarpal portal, usually employing the 4/5 midcarpal portal. Angulation, translation, and gapping can be seen on the capitate articular surface of the scaphoid, but are not seen on the radial side. A reduction maneuver of extension and radial deviation with volar wire stabilization of the scaphoid often restores alignment. If a manipulative reduction is insufficient, the K-wire is withdrawn to the volar side of the fracture and retained for later advancement across the reduced fracture. Additional K-wires in one or both fragments, as well as percutaneously inserted snaps or elevators, can help restore alignment. The volar wire is then advanced to stabilize the fracture. A screw is then placed percutaneously as described above. 

Open Reduction and Internal Fixation of Proximal Pole Scaphoid Fractures

A meta-analysis has demonstrated that the relative risk of nonunion for proximal pole fractures (Herbert B3) was 7.5 times more when compared with more distal fractures when all were managed nonoperatively (Fig. 43-28). This finding has been challenged recently by Grewal et al. with their study demonstrating an increased time to union but similar union rates for proximal pole fractures compared to other scaphoid fractures. Temporary interruption of the blood supply to the proximal fragment is virtually certain with proximal pole fractures but, if stabilized, the proximal pole has the capacity to revascularize and heal. Proximal pole fractures are uncommon and the use of operative management is based on intuition more than data. 

A: A fracture through the proximal pole of the scaphoid confirmed on MRI. B: Screw fixation of the proximal pole fracture.

For proximal pole fractures, most authors recommend operative treatment using a small open dorsal approach to ensure alignment and to allow access to the proximal fragment. Commonly, a straight 3 to 4 cm incision is centered over the dorsal aspect of the wrist after checking the level of the scapholunate junction with the fluoroscope. The extensor pollicis longus tendon is routinely unmoved. The dorsal capsule is then incised and the scaphoid exposed. Care is taken throughout this approach to avoid injury to the dorsal ridge vasculature and scapholunate ligament. Otherwise, the technique for fixation is as for ORIF above. 

Authors’ Preferred Treatment for Scaphoid Fractures (Algorithm 43-1)

Authors’ preferred treatment for scaphoid fractures.

Management of Expected Adverse Outcomes and Unexpected Complications Related to Scaphoid Fractures

Malunion

Some displaced scaphoid fractures can malunite, usually with a humpback deformity (Fig. 43-29). Pronation or ulnar translation of the distal fragment is less commonly seen. The effect of this malalignment on symptoms and wrist function is debatable. One cadaveric study has suggested that scaphoid malunion results in a notable reduction in wrist motion, and a few small series of osteotomy for scaphoid malunion have reported improved motion and function with decreased symptoms. However, studies of nonunions treated with no attempt to correct alignment (e.g. with Russe grafts) found no correlation of function or arthrosis with scaphoid malalignment in both the short and long term. In contrast, Ten Berg et al. demonstrated that uncorrected malunion resulted in higher dysfunction secondary to resultant DISI deformity. 

CT scan of a scaphoid fracture that has healed with a humpback deformity. The intrascaphoid angle measures 67 degrees.

Patients with scaphoid malunion are believed to be at risk of wrist pain, reduced wrist extension, and diminished grip strength. One study has demonstrated that the loss of wrist extension is proportional to the angular deformity, while another has suggested that the degree of DISI deformity correlates with symptom severity. Standard radiographs are the first line of investigation, with further imaging in the form of CT often to better delineate the deformity. Useful measurements include: 

• Lateral intrascaphoid angle (see Fig. 43-18A): An angle greater than 35 degrees is used as a cut-off for displacement; noted to have poor interobserver reproducibility on both CT and MRI
• Height-to-length ratio (see Fig. 43-18C): Found to be have the best reproducibility for assessing angulation

Alternate measurements found to be of limited use include the dorsal cortical angle (see Fig. 43-18B) and the AP intrascaphoid angle. It should be noted that both short- and longer-term retrospective studies have demonstrated no correlation between any outcome measure and the degree of radiologic deformity. 

The clinical consequences of malunion are not completely clear. Forward et al. reported on the clinical outcome at 1 year of 42 consecutive patients with a malunited scaphoid waist fracture that had all been managed nonoperatively and found no significant correlation between any outcome measure (range of motion, grip strength, patient reported outcome measures [PROMs]) and any of the three measures of malunion (height-to-length ratio, dorsal cortical angle, lateral intrascaphoid angle). Similar results have been reported in the longer term. 

An osteotomy is considered when there is objective impairment (e.g. loss of extension) that seems directly related to the scaphoid malalignment. Lynch et al. reported a technique of corrective osteotomy that corrects the intrascaphoid angles, restores palmar length to the scaphoid, and reduces DISI deformity of the carpus. They claim that this method could potentially prevent or delay the onset of arthritis in young patients with high functional demands. However, a recent study evaluating 17 patients followed for a mean of 21 years demonstrated no difference in wrist outcomes and disability scores between malunions treated operatively and nonoperatively. 

Nonunion

Scaphoid nonunion leads to a specific type of posttraumatic wrist arthrosis labeled scaphoid nonunion advance collapse (SNAC) similar to the arthrosis that develops after scapholunate ligament injury. The development of SNAC (Fig. 43-30) is extremely variable in terms of the rapidity of progression and the association with pain, stiffness, disability, or union. One rationale for operative treatment to gain union of the scaphoid is to delay or prevent arthritis, but it is unclear if achieving nonunion can achieve these goals, particularly if the nonunion is more than a year old. 

Scaphoid nonunion advanced collapse (SNAC) of the left wrist.

The natural history of scaphoid fracture nonunion is unknown as most patients present again because of new or ongoing symptoms. The quoted rate of nonunion is variable due to a lack of agreement regarding the criteria for union and the imaging modality that should be used. Nonunion is said to occur in approximately 10% of all scaphoid waist fractures, but the rate is much lower for nondisplaced fractures and approaches zero when a nondisplaced fracture is adequately treated and protected. Displaced fractures have a 50% nonunion rate, with an increased rate also seen with proximal pole fractures (Table 43-13; Fig. 43-31). Other proposed risk factors for nonunion of scaphoid waist fractures include delayed diagnosis or treatment. 

An established scaphoid proximal pole fracture nonunion found on MRI.

Fisk described the triplane angulation and subsequent humpback deformity of the scaphoid that results from established nonunion where the proximal scaphoid rotates dorsally into extension and the distal part faces downward in flexion. Impingement between the palmarflexed scaphoid distal pole and the radial styloid process leads to the development of radiocarpal osteoarthritis. At the same time, the unsupported carpus collapses into a DISI deformity with increasing subluxation and secondary arthritis of the midcarpal joint (Fig. 43-32). The articulation of the proximal pole with the radius and the radiolunate joint are relatively spared. 

An established scaphoid nonunion with associated DISI deformity.

Some scaphoid nonunions have minimal or no deformity, there seems to be a firm fibrous union between the fracture fragments, and the progression to symptoms and the necessity for treatment is unclear. According to the Herbert and Fisher classification (see Fig. 43-24), type D1 fractures are scaphoid fibrous nonunions that commonly occur in stable fractures following cast immobilization. 

Type D2 fractures are an established sclerotic scaphoid nonunion. These injuries are usually unstable with a progressive deformity that leads to the development of wrist arthritis (SNAC). Two patterns of nonunion displacement have been described, dorsal or volar, with the location of the fracture line relative to the dorsal apex of the scaphoid ridge predictive of the pattern. Distal scaphoid waist fractures, with large triangular bone defects, are associated with the volar pattern, with the development of a humpback and/or DISI deformity. Proximal scaphoid waist fractures, with much smaller, flat, crescent-shaped bone defects, are associated with the dorsal pattern. Similarly, one study has found that carpal instability after a scaphoid fracture nonunion is related to whether the fracture line passes distal or proximal to the scaphoid apex. 

Many scaphoid nonunions are unnoticed fractures that present with symptoms either gradually or after a later fall. Missed diagnosis is not uncommon and often results in additional morbidity from secondary changes, including nonunion, collapse deformity, and degenerative arthritis. Patients usually have radial-sided wrist pain, reduced wrist motion with pain at the limits of motion, and reduced grip strength. 

A radiographic diagnosis of nonunion cannot be made confidently until 6 to 12 months after injury although some may argue that union can be confirmed if the patient is asymptomatic and the original fracture line is no longer visible. Prior to that time, radiographs may demonstrate the classic findings of nonunion, including widening of the fracture gap, cystic changes, and fracture-line sclerosis even when the fracture is healing. Radiographs can be compared with images of the opposite unaffected wrist, particularly for preoperative planning. Other options for diagnosing nonunion include USS, CT, or MRI. One study investigated the use of real-time linear USS in determining fracture-site movement in 27 patients with a scaphoid nonunion, of which 24 had had surgical treatment, and found the technique to be 100% specific for visualization of movement at the fracture site although it was of no benefit in assessing proximal pole nonunion. 

Although MRI is utilized in the diagnosis of scaphoid AVN, it has not been found to be superior to CT for assessing fracture nonunion, alignment, and for comparison of findings before and after nonunion surgery. Sagittal images from scans are considered to provide the best method of evaluating the location of the nonunion and the degree of collapse. The lateral intrascaphoid angle and the height-to-length ratio of the bone help determine angulation and collapse of the scaphoid, with an angle of more than 35 degrees associated with an increased incidence of arthrosis even in nonunions that eventually progress to union. One study has documented a good correlation between preoperative proximal pole sclerosis on CT with AVN and subsequent fracture union, with a specificity of 100%, but with a sensitivity of 60% and an accuracy of 74%. CT is also cheaper and more readily available in many centers. The only definitive test for confirming AVN is the observation at surgery of the presence or absence of bleeding from bone. 

Management

The goals of management are to relieve symptoms, correct the carpal deformity, achieve union, and hopefully delay the onset of wrist arthrosis. The major principles to follow are: 

• Make an early diagnosis
• Perform a complete resection of the nonunion
• Correct the deformity secondary to carpal collapse and carpal instability
• Preserve the blood supply throughout
• Achieve bone apposition by an inlay graft
• Achieve stability with screw fixation

Treatment options include fixation without bone grafting, fixation with either a vascularized or nonvascularized graft, and finally wrist salvage procedures (Table 43-14). There is limited data on the ability of current techniques to either reduce symptoms or limit the onset of wrist arthrosis, as well as when salvage procedures should be utilized primarily. Poor prognostic indicators are a prolonged nonunion time, prior failed surgery requiring revision, the more proximal the nonunion, and the absence of punctate bleeding at the proximal pole during surgery. Generally, the number of punctuate bleeding points is a good indicator of bone vascularity. When the proximal pole is completely avascular, the likelihood of successful healing with a graft may be substantially diminished and an alternative salvage procedure should be considered. 

The stable scaphoid nonunion is characterized by a firm fibrous nonunion that prevents deformity, with the risk of osteoarthritis being small. The indications to manage patients surgically with a stable nonunion are limited to improvement in symptoms, prevention of progression to an unstable nonunion, or delaying the development of degenerative changes. The earlier the surgery is performed, the lower the incidence of secondary osteoarthritis. 

For stable nonunions, structural graft support is not required, simply a graft that will promote union; although some have suggested no graft at all. Treating stable nonunions ordinarily gives good results using either an open or percutaneous technique. 

Bone Grafting

CT and radiographs of the opposite side can help determine the optimal size and shape of the bone graft required. The standard palmar approach (see above) with the advantage of avoiding damage to the blood supply can be used for most reconstructions of unstable scaphoid nonunions, except in fractures involving a small proximal pole fragment. Techniques of palmar and radiopalmar bone grafting have been developed to correct scaphoid malalignment and to restore normal scaphoid length. Failure to correct the humpback deformity results in intraoperative difficulties because the screw cannot be adequately placed and will cut out, leaving residual instability. Even if the nonunion heals, the malunited scaphoid may lead to degenerative arthritis compared with a scaphoid that has healed with correct alignment, although the recent literature provides conflicting results. Although AVN of the proximal fragment may potentially affect the healing potential of a scaphoid, diminished vascularity of the proximal scaphoid is not a contraindication to a palmar inlay bone graft. If fracture union can be achieved, the relative avascularity will improve. There is mounting evidence that even in cases with MRI-suggested AVN and intraoperative findings of impaired vascularity, scaphoid union can be achieved with and without vascularized grafting. 

There are a number of methods of bone grafting in use but none has been found to be superior in terms of achieving union. Prior to the introduction of modern fixation methods, the Matti–Russe inlay graft was used in the treatment of scaphoid nonunion (Fig. 43-33), but this technique does not usually correct malalignment. Anterior wedge-grafting procedures, with initial reduction of the lunate and temporary pin fixation, are now commonly used to correct humpback deformities. Screw fixation has generally been found to give superior union rates when compared to K-wire fixation when using nonvascularized graft. Several authors have reported the use of volar or dorsal scaphoid plating (Fig. 43-34) to improve nonunion stability when grafting. These results are encouraging but no widespread comparative trials currently exist. 

Standard Russe bone graft. His technique relied on packing a corticocancellous bone graft into a trough curetted through the volar cortex of both fragments. Because the volar cortex is often foreshortened by erosion of the fragments, loss of length is difficult to correct without introducing a cortical graft. Modified Russe winged graft can be impacted into a volar trough to lengthen the scaphoid.

Radiograph of a scaphoid plate. (Courtesy of Mr Mike Hayton—Upper Limb Unit, Wrightington, UK).

No correlation between donor sites (iliac crest, distal radius) and union have been demonstrated. Some authors advocate taking corticocancellous graft from the anterolateral corner of the radial metaphysis rather than the iliac crest, as it allows harvesting from one incision with reduced donor-site morbidity and comparable union rates. Cohen et al. recently reported good clinical and radiologic results in 12 patients with established scaphoid waist nonunions using ORIF with only cancellous interposition graft from the ipsilateral distal radius. Potential disadvantages of nonvascularized grafts include increased nonunion rates in the presence of AVN and short-term donor-site morbidity associated with graft taken from the iliac crest. 

Vascularized bone grafts from the distal radius (radial artery), distal ulna (ulnar artery), and based on the pronator quadratus have been described. Union rates following distal radial pedicle grafts range from 27% to 100%, with poor rates seen when used for AVN. New free vascularized grafts from the iliac crest and the medial femoral supracondylar zone have been reported, with three studies documenting superior union rates of the medial femoral supracondylar graft when compared to a vascularized graft from the distal radius. 

A recent randomized controlled trial compared vascularized (distal radius) with nonvascularized (iliac crest) bone grafting for scaphoid nonunion and found a 100% union rate in the nonvascularized group, with a rate of 85% in the vascularized group (p > 0.05). No significant differences were found in time to union or function. Recent meta-analyses evaluating the utility of vascularized versus nonvascularized grafts have found similar union rates between these techniques. 

Operative Technique

For a stable scaphoid nonunion, we prefer an open palmar approach using a straight incision as opposed to the curved incision described by Russe. However, no evidence currently exists to guide the choice of approach. The incision is based over or radial to the flexor carpi radialis from the scaphoid tubercle to the distal radius. The sheath of the flexor carpi radialis tendon is incised and the tendon retracted ulnarly. Directly beneath the tendon lies the palmar capsule of the wrist, just above the scaphoid. The capsule should be incised longitudinally. The superficial palmar branch of the radial artery is distal at the end of incision and needs to be ligated in cases of wider exposure of the distal scaphoid. Stable scaphoid nonunions might not be visible macroscopically and often need sharp division with the knife. It is useful to check the site of a nonunion as fusion of the proximal pole of the scaphoid with the lunate or the scaphoid distal pole and trapezium have been undertaken assuming that this joint was the site of nonunion. It is important to prepare the nonunion surfaces by removing any fibrous tissue and sclerotic bone. We usually leave the dorsal cartilage in place. This provides a hinge and facilitates assessment of the scaphoid length. In most cases of stable nonunion, cancellous bone graft from the distal radius usually provides sufficient volume as structural support is not required, although iliac crest bone graft can be used if necessary. Screw fixation of the scaphoid is then used. Immobilization in a cast or splint is not required postoperatively except in occasional cases for pain relief. 

For an unstable nonunion, we feel a volar approach is necessary to correct the humpback deformity. The nonunion gap is exposed and debrided, and the fracture fragments are mobilized. It is best to leave a cartilage hinge posteriorly to provide a fulcrum around which the fragments may be hinged open although this is often not possible in older, unstable scaphoid fractures. If the hinge is released in an effort to regain all of the scaphoid length, the fracture fragments will become extremely unstable and difficult to align. Furthermore, the gap between the two fragments may be too great for the scaphoid to revascularize the proximal pole. The wrist is extended, and the two fragments are gently distracted with small spreaders. This maneuver usually achieves adequate correction of the carpal deformity and a satisfactory improvement in wrist extension. Provided reasonable correction is achieved and that the wrist extends to at least 45 degrees, most patients achieve satisfactory clinical results. The fracture surfaces are freshened with a small osteotome, bur, or curette. We prefer a corticocancellous wedge graft from the iliac crest. This is an interposition graft, which is inserted on the palmar surface and serves to bridge the fracture gap and correct any displacement or angulation of the scaphoid that has occurred. Vascularized bone grafts from the distal radius (radial artery) or distal ulna (ulnar artery), and medial femoral condyle have also been described, though we would suggest the pronator quadratus graft. 

To correct angular deformity and restore normal scaphoid length, the amount of resection and size of the graft can be calculated preoperatively by CT scans. The indications for interposition grafting include gross motion at the nonunion site, scaphoid resorption, and loss of carpal height. Most commonly, the operative procedure involves an anterior interposition bone graft, with the size based on comparative scaphoid views of the opposite wrist and intraoperative measurements. The width and depth of the defect is measured, and a graft of the exact size is harvested with an osteotome. Oscillating saws should not be used, as thermal necrosis of the graft can occur. With the wedge graft in place and the scaphoid reduced and held with a K-wire, a compression screw is inserted. Internal fixation with K-wires alone is usually not successful as compression is required to achieve union. However, if the graft shows a tendency to rotate, additional fixation with a K-wire may be required. If there is a severe or longstanding DISI deformity with an RL angle greater than 20 degrees, additional pinning of the lunate to radius for 6 to 8 weeks is advised. It may be difficult to completely correct carpal instability in longstanding cases, and these patients may be better served by various salvage procedures. Finally, a partial radial styloidectomy can be performed in patients with radiologic signs of stage I radioscaphoid arthritis, this being arthritis that is limited to the scaphoid and radial styloid. This is undertaken to relieve pain arising from arthritic joints or osteophyte impingement. If there are no radiologic signs of arthritis, a styloidectomy should not be undertaken at the same time as a scaphoid reconstruction often relieves symptoms. 

With stable fixation, postoperative immobilization is usually not required but a Colles’ cast can be used if there is doubt about stability or pins have been used across the radiocarpal joint. 

Outcomes

The quoted union rate following treatment for scaphoid fracture nonunion are wide ranging, with a recent systematic review concluding an 80% union rate for bone grafting without fixation and a 84% rate for grafting with internal fixation. 

One scientific exhibit presented data on stable scaphoid-delayed unions or nonunions (defined by nonunions that were well aligned and without extensive sclerosis or bone resorption at the nonunion site) that were treated by percutaneous screw fixation with good results. One study of 27 patients with established scaphoid nonunions (well-aligned fractures with extensive local bone resorption) managed with percutaneous screw fixation alone reported good results with all fractures uniting at an average of 3 months. Additional study is needed to determine which nonunions are amenable to this approach. 

The quoted success rates of achieving union with internal fixation and bone grafting for unstable nonunions range from 60% to 95%. The differing rates may be explained by the heterogeneous nature of patient demographics, fracture nonunion characteristics, or the acknowledged difficulty in defining union. Two studies have implicated smoking as a reason for failure of nonunion surgery. 

Avascular Necrosis

AVN of the scaphoid can occur as a late complication of scaphoid fractures, especially those involving the proximal pole. Occasionally, AVN may occur without a fracture, either as a complication of a scapholunate ligament injury or as an idiopathic condition known as Preiser disease. 

The typical symptoms of AVN are increasing pain and stiffness of the wrist. Standard radiographs demonstrate a small, deformed proximal pole fragment with cystic changes and areas of sclerosis. The value of MRI to diagnose AVN in the routine management of scaphoid nonunions is debated. Current best evidence has not demonstrated that MRI can reliably or accurately diagnose AVN, with MRI findings not prognostic. 

The natural history of scaphoid AVN is not known and it is not known if operative treatment can alter the natural course of the disease. One treatment option is a vascularized bone graft. Arora et al. reported the use of free vascularized iliac bone graft for the management of 21 patients with AVN and nonunion of the scaphoid for which conventional bone grafting had failed, achieving union and good symptom relief in 16 patients. 

The bone graft can be harvested dorsally through the second dorsal compartment of the distal radius, anteriorly in the form of a pronator quadratus graft, or from the second metacarpal. An additional graft site recently described is the vascularized medial femoral condyle. No conclusive superiority of any one graft has been demonstrated but a trend to improved outcomes with femoral grafting was recently reported in a large meta-analysis. Conflict remains regarding the necessity of vascularized grafts for nonunions with AVN; however, recent systematic reviews suggest improved union rates compared to nonvascularized grafts. It is important to adhere to the basic principles of nonunion treatment with meticulous preparation and stabilization of the nonunion site. There has been one report of using arthroscopic debridement in managing these patients. 

Future Directions Related to Scaphoid Fractures

Since the last edition of this publication, there have been numerous publications on the diagnosis of suspected scaphoid fractures and we continue to lack a consensus reference standard for the diagnosis of true fractures among suspected scaphoid fractures. More sophisticated imaging to date continues to identify more abnormalities that are difficult to interpret. Consequently, it is becoming increasingly clear we need to accept that we are ultimately dealing with probabilities rather than certainties in the diagnosis of suspected scaphoid fractures. Such an approach would no longer seek to diagnose the presence or absence of a fracture definitively. Rather, the goal would be optimal NPV and PPV with the goal of reaching certain accepted thresholds. Since the pretest odds of a fracture (or the prevalence of true fractures among suspected fractures) have a substantial effect on the PPV, future research should build on the attempts to develop clinical prediction rules. These rules should employ demographic and clinical factors predictive of a true fracture to better identify patients in whom imaging will have an acceptable NPV and PPV. In addition, given the absence of an accepted reference standard, future research should continue to use latent class analysis to estimate diagnostic performance characteristics. 

Regarding the decision between operative or nonoperative treatment of nondisplaced/minimally displaced fractures of the scaphoid waist, the following issues merit ongoing investigation: the safety of a shorter duration of cast wear and the use of casts or even splints that are less cumbersome (e.g. thumb free); differences in the quality of life, cost effectiveness, and the safety of earlier return to work or sport; the definition, diagnosis, and prevalence of “minimally displaced” fractures of the scaphoid waist; and a comparison of operative and nonoperative treatment for this subset of fractures. 

Regarding scaphoid nonunion, more data is needed on the long-term outcome, including patient-reported measures, following surgical intervention. There are also ongoing controversies regarding the use of vascularized bone grafts in reconstructive procedures, as well as when to progress to salvage procedures. 

Scaphoid Fractures: Pearls and Pitfalls

• Male gender and sports injuries are risk factors for an acute fracture of the scaphoid.
• Clinical prediction rules might aid in the assessment of the suspected fracture.
• Displacement of scaphoid fractures may be difficult to diagnose and CT or arthroscopy can be helpful.
• The criteria for displacement, in particular minimal displacement, needs to be further investigated and better defined.
• Nonoperative management is routinely employed for suspected scaphoid fractures and tubercle fractures.
• Percutaneous fixation for undisplaced or minimally displaced waist fractures may reduce the time in cast, increase the rate of return to function, and increase the rate of union.
• Surgical management is recommended for displaced scaphoid fractures, proximal pole fractures, comminuted fractures, and fractures that are part of a greater perilunate injury.

Other Carpal Fractures

Triquetral Fractures

Introduction to Triquetral Fractures

Triquetral fractures are the second most common fracture of the carpus with avulsion fractures (representing in essence a benign “wrist sprain”) accounting for over 90% of all triquetral injuries. Less common patterns of fracture include: 

• Transverse fracture of the triquetrum as part of a perilunate dislocation, although more frequently dorsal displacement is seen
• Impingement shear fracture type
  • Ulnar impaction: Ulnar styloid against the dorsal triquetrum, which occurs with the wrist in extension and ulnar deviation, particularly when a long ulnar styloid is present
  • Triquetrohamate impaction: Hamate against the posteroradial projection of the triquetrum, occurs through compression of the wrist in forced dorsal and ulnar extension while the forearm is pronated

Assessment of Triquetral Fractures

Patients present with pain and tenderness localized over the region of the triquetrum. Standard scaphoid views will detect most triquetral fractures, with dorsal avulsion fractures of the triquetrum often found on the oblique or lateral views. PA radiographs of the wrist are useful in identifying transverse body fractures; however, they will often not detect avulsion fractures of the triquetrum due to the normal superimposition of the dorsal lip on the lunate. Additional views that can aid the diagnosis include an oblique pronated lateral radiograph that will project the triquetrum even more dorsal to the lunate. Secondary imaging modalities are often not necessary, although CT for further delineation of body fractures is useful. Occult triquetral fractures can be identified when CT and MRI are used in the detection of occult scaphoid fractures. 

Treatment of Triquetral Fractures

Triquetral avulsions are managed with a splint for comfort only and active self-assisted stretches as comfort allows to limit stiffness. Triquetral body fractures associated with carpal disruption often require internal fixation. 

Lunate Fractures

Introduction to Lunate Fractures

Lunate fractures account for less than 1% of all carpal fractures and most occur as part of a perilunate injury. 

Clinical Anatomy

The lunate is the middle bone of the proximal carpal row, acting as a keystone in the well-protected concavity of the lunate fossa of the radius, anchored on either side through interosseous ligaments that connect to the scaphoid and triquetrum. Distally, the convex capitate head fits into the concavity of the lunate. The joint reaction forces from the capitate and radius move the lunate ulnarly. The proximal pole of the hamate has a variable articular facet on the distal ulnar surface of the lunate, and ulnar deviation increases the degree of contact of these two bones. 

The vascular supply of the lunate is primarily through the proximal carpal arcade, with the current literature suggesting that approximately 80% of lunates receive vessels from both the dorsal and palmar surface, with the remaining 20% from the palmar surface only (see Table 43-3). It is said that this limited blood supply renders the lunate vulnerable to AVN and yet AVN is almost unheard of after lunate or perilunate dislocations, presumably because the palmar radiocarpal arch usually remains intact as the dislocation is through the space of Poirier. The lunate blood supply is frequently endangered by common dorsal approaches to the wrist, but the blood supply from the palmar radiocarpal arch is usually sufficient. 

Kienböck’s Disease

Kienböck’s disease is an eponym for idiopathic avascular osteonecrosis of the lunate. It usually has an insidious onset without a history of injury; however, diagnosis is sometimes made after a simple fall that fractures the necrotic bone. Osteonecrosis may be the result of interruption of the vascular supply to the lunate, which shows no radiographic evidence of injury until sclerosis and osteochondral collapse. The condition is more common in patients with an ulnar minus variant. 

Some believe that unrecognized and untreated fractures of the lunate lead to Kienböck’s disease, predominantly due to the cadaveric work of Verdan who applied strong forces to cadaver bones and observed that the resulting fractures were not visible on standard radiographs but only on histology. However, others have questioned these findings, with one study suggesting that early venous congestion, not fracture, of the lunate was responsible for the pathogenesis of Kienböck’s disease. The lunate necrosis after perilunate dislocation is probably due to impairment of the arterial vasculature. 

Assessment of Lunate Fractures

Most patients with fractures of the lunate have a history of a hyperextension injury such as a fall on the outstretched hand. Patients present with pain and tenderness localized over the region of the lunate and triquetrum. 

Imaging

Standard scaphoid views are the primary investigation for suspected lunate fractures. Some injuries may be difficult to visualize early, as an undisplaced fracture can be obscured by superimposed structures: 

• The palmar cortical line of the radial styloid is aligned with the division between the dorsal and palmar thirds of the lunate where a transverse fracture often occurs
• The AP view of this is in a plane almost perpendicular to the fracture, which is overlapped by the rims of the distal radius and is therefore not apparent
• The palmar horn of the lunate may also be hidden by the pisiform and scaphoid shadows

Given this, there must be a low threshold for further imaging when the diagnosis is in doubt. Bone scan will be positive within 24 hours of injury. However, CT will provide the most precise detail regarding any fractures, as well as any osteonecrotic changes that may need to be differentiated from a primary fracture or secondary fracture associated with fragmentation. Arthroscopic examination permits a direct assessment, including that of the articular surfaces and the intrinsic ligaments. 

Classification

Lunate fractures can be difficult to describe and part of the difficulty is that the fragmentation that occurs in Kienböck’s disease can be confused with fractures. However, acute fractures of the lunate were classified into five groups by Teisen and Hjarback: 

Fresh fractures of the lunate include dorsal and palmar horn avulsion fractures that occur more often in the radial corner than in the ulnar corner. Fractures of the body are usually transverse in the coronal plane. The more common of these is between the middle and palmar thirds of the body. 

Treatment of Lunate Fractures

Nonoperative management in cast for approximately 4 weeks is suitable for most isolated lunate fractures with nonunion rarely reported. A transverse fracture of the body will heal if it remains nondisplaced, particularly in adolescents. 

Indications for ORIF include displacement and/or associated carpal instability. If there is evidence of separation of the lunate fragments by the capitate, union will not occur and the risk of AVN is markedly increased. Although the efficacy of internal fixation of the lunate is unproven and the obstacles to successful reduction and fixation are substantial, the consequences of inaction are as to be expected. Distraction with an external fixator may facilitate reduction of the lunate fragments, particularly in the chronic setting. 

Nonunion of a lunate body fracture is rare, as most will progress to Kienböck’s disease. If this occurs, the treatment includes radial shortening, radial wedge osteotomy, or ulnar lengthening in the early stages, with carpal arthrodesis if the condition is advanced. 

Uncommon Carpal Fractures

Carpal fractures other than those of the scaphoid, lunate, and triquetrum are rare. The known facts about these are summarized in Table 43-15. 

For most isolated, undisplaced, or minimally displaced carpal fractures we prefer nonoperative management. We routinely use a standard Colles’ cast or wrist splint, depending on the requirements of the patient, for a period of approximately 4 weeks followed by routine mobilization. For simple avulsion fractures, immediate motion, and a splint as required for discomfort is sufficient. For displaced fractures, which are routinely associated with other osseous or soft tissue injuries of the carpus, we prefer closed or open reduction, with internal fixation. 

Other Carpal Fractures: Pearls and Pitfalls

• Triquetral fractures are the second most common carpal fracture following a fracture of the scaphoid.
• Routine scaphoid radiographs detect most carpal injuries.
• A thorough assessment for other osseous and ligamentous injuries of the carpus is necessary.
• Most of the other carpal fractures can be managed nonoperatively with good results.

Carpal Ligament Injuries

There are various classifications for carpal malalignment and carpal ligament injuries, which are discussed in pages 1601–1602. A variety of imaging modalities are used when carpal ligament injury is suspected. Standard scaphoid radiographs with additional deviated views of the wrist, and possibly a clenched-fist PA view form the primary investigation. MRI is imperfect for carpal ligament injuries and wrist arthroscopy is considered the reference standard, but it is not clear what to do with so-called partial injuries and how these can be distinguished from normal variations or age-related changes. 

Scapholunate Dissociation

Introduction to Scapholunate Dissociation

SLD is the most common form of carpal ligament injury, with dynamic scapholunate instability the most common cause of instability in adolescents and young adults. Instability can occur in isolation or in association with a fracture of the carpus or distal radius. The most common mechanism of injury involves hyperextension of the wrist with associated ulnar deviation and intracarpal supination leading to injury of the scapholunate interosseous and palmar ligaments. A previous injury, repetitive strain on the carpus, or the presence of acute or chronic synovitis appears to alter the magnitude of force required to cause ligamentous disruption, so much so that the presenting event may be following a trivial injury. Although 40% of distal radial fractures may have concomitant SL injuries, even trivial wrist sprains may be associated with SL injuries in up to 5% of patients. 

SLD describes a spectrum of injuries ranging from ligamentous sprains through to dislocation of the scaphoid. A variety of ligament disruptions can occur including one or more of the scapholunate interosseous ligament, the radioscapholunate ligament, the radioscaphocapitate ligament, the scaphotrapezium–trapezoid ligament, the DRC ligament, and the dorsal intercarpal ligament. Disruption of the scapholunate interosseous ligament leads to dyskinesia between the scaphoid and lunate, ultimately resulting in progressive widening of the scapholunate joint with time. The clinical consequences of the injury depend on the tightness or laxity of the capsuloligamentous system of the wrist, as well as the presence of any associated palmar radiocarpal or midcarpal ligament damage. 

Assessment of Scapholunate Dissociation

Patients will often present with localized wrist pain and swelling following a fall onto an outstretched hand with the wrist undergoing a forced hyperextension. There will be tenderness in the region of the scaphoid and lunate. Movement of the wrist may be minimal, with pain on flexion–extension or radioulnar deviation and an audible clunk or click heard. A full assessment of the entire carpus and distal radius and ulna is necessary as there may be an associated fracture. A clinical deformity at the wrist may be apparent and a full neurovascular assessment is imperative, as acute carpal tunnel syndrome can occur with associated carpal fractures and dislocations. 

Signs and Symptoms

Clinical findings can be subtle, and the classic features of carpal instability may not be apparent without provocative stress testing. A simple general provocative maneuver is a vigorous grasp that induces pain, an audible clunk or click, a dorsal deformity in the region of the proximal scaphoid, and reduced power with repetitive grip strength testing. A positive Kirk–Watson (scaphoid shift) test is highly suggestive of scapholunate instability (see Fig. 43-12), although not absolutely specific for SLD as it may reposition the entire proximal carpal row if the row, rather than the individual scaphoid, is unstable. In addition, in individuals with lax ligaments there may be false-positive signs of dorsal subluxation of the scaphoid that are not pathologic. Generalized ligamentous laxity may be present in patients with true SLD as many wrists with an injury have some form of pre-existing ligamentous laxity. 

Imaging

The six standard views for carpal instability are mandatory in the assessment of suspected SL instability. Clenched-fist views and contralateral wrist views can aid the diagnosis. The following should be assessed (see pages 1606–1609): 

• A scapholunate gap of more than 3 mm is suggestive of instability, with a gap of over 5 mm diagnostic of SLD if there is a positive cortical ring sign (Fig. 43-35). The increased gap between the scaphoid and lunate has been named the Terry Thomas sign after the gap-toothed smile of the British comedian. It is suggested that the gap should be compared to the uninjured opposite extremity, particularly in the absence of a dorsiflexed lunate, which is most likely nontraumatic.
   

  Figure 43-35

  Scapholunate instability with an increased scapholunate gap (Terry Thomas sign) found on the AP view.

  

  Figure 43-35

  Scapholunate instability with an increased scapholunate gap (Terry Thomas sign) found on the AP view.

  

  X
• The appearance of the scaphoid
  • A positive cortical ring sign is when the distal scaphoid tubercle is seen end-on with a PA view, suggestive that the scaphoid is flexed
• A scapholunate angle of more than 60 degrees is suggestive of instability, with an angle of over 80 degrees diagnostic of SLD (see Fig. 43-35)
• A radioscaphoid angle of greater than 60 degrees
• The appearance of the lunate
  • DISI deformity (see Fig. 43-35) where the lunate is extended (dorsally angulated) is associated with an SLD (see Table 43-4)
  • A normally positioned lunate projects as a quadrilateral shape on the neutral PA radiograph; however, the shape appears triangular when the lunate is malrotated and is often associated with a perilunate dislocation
• A capitolunate or radiolunate angle of more than 15 degrees is suggestive of instability, with an angle greater than 20 degrees diagnostic
• Gilula’s lines for ligamentous instability (see Fig. 43-15)
• Exclude associated fractures of the radius or carpus (Fig. 43-36), especially in younger patients
  • An ulnar positive variance of more than 2 mm in nonosteoporotic patients with an intra-articular fracture of the distal radius has been found to be predictive of a severe scapholunate injury
   

  Figure 43-36

  Radiographs of the wrist post manipulation for a fracture of the distal radius.

  

  Figure 43-36

  Radiographs of the wrist post manipulation for a fracture of the distal radius.

  

  X

Scapholunate instability with an increased scapholunate gap (Terry Thomas sign) found on the AP view. A DISI deformity and an increased scapholunate angle are found on the lateral view.

Radiographs of the wrist post manipulation for a fracture of the distal radius. An increased scapholunate gap indicative of SLD is seen and was confirmed intraoperatively.

The diagnostic acumen of these radiographic relationships fluctuates based on the values chosen, with higher thresholds understandably increasing the sensitivity and specificity of the diagnosis. A predictive sensitivity of 43% to 81% and corresponding specificity of 80% to 93% have been documented in the setting of a 2.5-mm scapholunate diastasis, a scapholunate angle larger than 60 degrees, and a radiolunate relationship of greater than 12. 

When these findings are not found on initial radiographs, stress testing with the provocative maneuvers discussed can be used with clenched-fist views or radioulnar stress views to determine the diagnosis and confirm dynamic SLD. Dynamic SLD is characterized by normal radiographs of the wrist, but with axial loading of the wrist a widening of the scapholunate gap is seen. Static instability is characterized by a widening of the scapholunate gap in an unloaded wrist and a scapholunate angle greater than 60 degrees. 

Secondary imaging modalities include fluoroscopy or cineradiography using standard and provocative stress motions. Arthrography has a high rate of false-positive and false-negative results and is therefore of limited use. MRI is helpful in discriminating the extent of ligament injury. Wrist arthroscopy can be used to determine the extent of ligament disruption and the presence of radioscaphoid arthritis, as well as to classify and treat the injuries. Arthroscopy has been shown to be effective in patients with suspected dynamic SLD (normal radiographs) for diagnosis and treatment in both acute and chronic cases, allowing assessment of both the ligament, and midcarpal and radiocarpal joints. 

Classification

SLD encompasses a spectrum of injuries ranging from grade I ligament sprains, through all grades of ligament destabilization, to injuries of multiple ligaments, and finally lunate dislocation. A greater arc injury encompasses SLD with a fracture of either the radial styloid or associated carpal bones. The classification of scapholunate instability considers whether the injury is acute or chronic and whether it is static or dynamic, as this can be helpful for guiding management. 

A static deformity does not occur with an isolated injury to the scapholunate ligament and typically requires disruption of multiple surrounding ligaments. In contrast, dynamic instability is often only apparent on stress imaging. Static instability occurs when the ligament is injured in conjunction with a multiple ligament disruption. One study has described four grades of ligament injury according to arthroscopic findings: 

• Grade I: Attenuation or hemorrhage of the ligament is seen from the midcarpal space but the bones are congruent. Conservative treatment is usually sufficient.
• Grade II: Incongruency between the carpal bones when viewed from the midcarpal space. Arthroscopic reduction and fixation is normally required.
• Grade III: Carpal malalignment in both carpal spaces with a gap between the carpal bones allowing entry of a 1-mm probe. Arthroscopic ± open reduction with fixation is required.
• Grade IV: Carpal malalignment in both carpal spaces with gross instability and a gap between the carpal bones allowing entry of a 2.7-mm arthroscope. Open reduction and fixation is needed.

An alternative classification was put forward by Kuo and Wolfe, which was subsequently used to define treatment (Table 43-16). 

Treatment of Scapholunate Dissociation

With appropriate treatment it is possible to avoid potential complications of an SLD injury including advanced scapholunate collapse and progressive, painful arthritis of the wrist. Different treatment options need to be considered based on the duration from the injury, the extent of ligamentous involvement, and the presence of associated carpal instabilities and/or fractures. The grade of ligament injury can guide treatment. However, a better guide is the duration since injury, which is best defined as: 

• Less than 4 weeks = acute
• 4 to 24 weeks = subacute
• More than 6 months = chronic

The primary goals of treatment are restoration of carpal alignment and the stabilization of the carpal bones to facilitate wrist mobility. The earlier ligament repair takes place the easier it is to perform a direct repair. 

Acute Scapholunate Dissociation

Patients with a grade I ligament injury but with no evidence of carpal instability can be managed effectively with cast immobilization. In patients with partial ligament tears but with instability present arthroscopically, cast immobilization is unsuitable as the scaphoid requires wrist extension to maintain reduction and the lunate requires wrist flexion. For these cases, percutaneous K-wire fixation in combination with cast immobilization for 8 weeks can be employed. One K-wire is placed from the scaphoid to the lunate and another from the scaphoid to the capitate. Pins can be placed into the scaphoid and lunate and used as joysticks to reduce the scapholunate joint. An 85% success rate in maintaining SL reduction has been reported in patients with a scapholunate interval that was greater than the unaffected wrist by 3 mm or less and in patients where the injury was less than 3 months old. Such injuries, even if not initially associated with obvious instability, can progress to scapholunate collapse. 

When the carpus cannot be reduced by closed methods, open ligament repair and pin fixation is recommended in all cases of acute SLD. Cadaveric studies have demonstrated that reduction of the scapholunate articulation is essential to the recovery of normal wrist kinematics after SLD. Soft tissue repair and reconstruction are popular because they attempt to restore the normal kinematics of the wrist, with current literature demonstrating superior results of direct ligament repair over ligament reconstruction. The technique of repair has changed considerably with the introduction of intraosseous suture retaining anchors allowing ligament attachment directly to the bone (Fig. 43-37). Results of primary open ligament repair by a dorsal approach are conflicting. Some authors advocate a combined dorsal and palmar approach suggesting improved reduction and outcome. 

Ligament repair for scapholunate instability using anchors placed into the lunate (or scaphoid, depending on where the ligament has ruptured), and the ligament is sutured back into position.

Bickert et al. reported on the short-term outcome of 12 patients following repair with a dorsal approach at a mean follow-up of 19 months and reported restoration of a normal scapholunate angle in 10 patients, with the mean range of motion at 78% of normal, the mean grip strength 81%, and eight patients with an excellent or good result. However, no correlation was found between functional and radiologic results, although one of the two poor results was associated with lunate necrosis. Outcome in the long term is unknown, although similar outcomes have been reported at 5 to 6 years after surgery. Some authors are advocates of management using an arthroscopic technique that can aid in confirming the diagnosis, as well as determine the location and extent of ligamentous damage, for example, palmar extrinsic ligament attenuation. However, whether this is superior remains unclear. 

Subacute Scapholunate Dissociation

For subacute SLD, the addition of local tissue may be necessary if the ligament has retracted or is deficient. Blatt’s technique (Fig. 43-38) uses a proximally based dorsal capsular flap retracted onto the scapholunate articulation, and this is sutured as tightly as possible to the distal pole of the dorsal aspect of the scaphoid to act as a tether. This flap can be added to the ligament repair process described earlier by placing nonabsorbable sutures from the lunate ligament remnant into the capsular tissue and then out through the scaphoid. An alternative method is to use a strip of tendon from the radial wrist extensors (extensor carpi radialis longus or extensor carpi radialis brevis), but tendon tissue is not an ideal ligament replacement with capsular tissue routinely preferred. Megerle et al. recently evaluated the long-term results of 50 patients treated with dorsal capsulodesis and reported immediate short-term improvements in SL and radiolunate angles, although the capsulodesis was unable to satisfactorily maintain reduction over time. 

Blatt’s technique of dorsal capsulodesis, with the scaphoid reduced a capsular flap is secured to the distal pole with an anchor.

Through a palmar approach, direct ligament repair using nonabsorbable sutures can be performed. If there is deficient tissue, a section of the flexor carpi radialis can be used to augment the repair process by placing drill holes through the proximal scaphoid and radial half of the lunate and passing one-half of the flexor carpi radialis tendon in a circular fashion to reinforce the dorsal and palmar ligaments. The radioscaphocapitate and radioscapholunate ligaments may be advanced into the gap. With a large, complete ligament tear associated with a gap of 5 mm or more, adjunctive palmar ligament repair is usually needed. A carpal tunnel incision extended slightly radially is performed, and the damaged area is identified with a probe inserted from a separate dorsal incision. The interval between the radioscaphocapitate ligament and radioscapholunate ligament is developed. Sutures may then be placed with intraosseous anchors into the scaphoid proximal pole or remnants of the interosseous membrane, which are then used to pull the radioscapholunate ligament against the proximal pole to hold the overreduction of the proximal scaphoid, which is stabilized by K-wires. The purpose of this palmar repair is to bring the dorsally subluxed and rotated proximal scaphoid in apposition with the palmar intracapsular ligaments. 

SL ligament reconstruction may also be performed using the SL axis method (SLAM). This technique was recently described with promising early biomechanical, cadaveric, and clinical results. A centrally compressive force is applied through ligamentoplasty using centrally drilled tunnels allowing improved strength to both the volar and dorsal aspects of the joint. This technique has also shown promise for use in chronic injuries. In a small series of clinical cases, Lee et al. demonstrated only one failure of recurrent SL gap (7%) with wrist strength reported as 62% of the contralateral side and a mean SL angle of 59 degrees. 

Whether the approach is dorsal, palmar, or combined, tight repair of the capsular structures is required. Internal fixation for a period of 12 weeks is preferred, supplemented with a below-elbow cast. After cast removal, a splint is worn as muscle strength and joint motion are restored with the aid of physiotherapy as required. Return to work or sports is best delayed for a minimum of 6 months, with continued protection being used during sports activities. 

Chronic Scapholunate Dissociation

The major issues associated with chronic SLD and instability are whether the ligaments can be directly repaired, any residual carpal dislocation is reducible, and the joint has developed arthritis. Whether to reconstruct or repair the ligamentous injuries in chronic SLD remains a contentious issue. Garcia-Elias originally described five questions that should be answered in an attempt to direct treatment: 

When possible, restoration of normal carpal anatomy by repair and reconstruction of the support ligaments of the wrist remains the preferred treatment. This requires sufficient local tissue for repair and correctable carpal instability. Partial or complete fusion of the wrist may be required when: 

• There is a fixed carpal deformity, for example, the rotational subluxation of the scaphoid or DISI deformity cannot be reduced
• The degree of ligament disruption and retraction precludes repair
• There are local degenerative changes of the radiocarpal and midcarpal joints
• The demands and expectations of the patient include heavy lifting or repetitive loading

There are many techniques described to treat chronic scapholunate instability. Current techniques for ligament reconstruction include repair with the dorsal capsular flap procedure, a palmar ligament reefing procedure, or combined dorsal and palmar procedures that add flexor or extensor tendon tissue to the repair site. The goal of each of these repair techniques involves the addition of local tissue to provide a collagen framework for future stability. Soft tissue reconstructions have several theoretical advantages that make them attractive alternatives to other procedures. In contrast to arthrodeses, soft tissue reconstructions provide a greater range of intercarpal motion (Fig. 43-39). 

A: Intraoperative photographs demonstrating clear disruption of the SL ligament with flexion of the scaphoid. B: A joystick K-wire was placed in the scaphoid to facilitate reduction. C: Significant force was applied to the joystick to ensure anatomic reduction. D: An FCR tendon graft was taken on the ipsilateral side through small transverse incisions E: This was secured to the lunate. F, G: Postoperative radiographs demonstrating the three-ligament tenodesis reconstruction technique and illustrating the reduction of the SL gap. A suture anchor was used to secure the FCR graft and a Blatt capsulodesis was performed over this reconstruction.

Tendon weave procedures and tenodeses (Fig. 43-40) have been attempted with variable success. Wrist extensor or flexor tendon augmentation procedures require placement of drill holes in the bone. In this procedure, drill holes are carefully placed in a dorsal-to-palmar direction through the scaphoid and lunate. Tendon strips are then passed through these holes to attempt a reconstruction of the ligament. The large holes required to pass tendon grafts can lead to a fracture of the carpus. An alternative technique is to take part of an extensor or flexor tendon and pass it through the capitate, scaphoid, lunate, and distal radius. Another technique is the reconstruction of the dorsal part of the ligament using a bone–ligament–bone autograft; however, clinical results are not particularly convincing. 

Tendon weaves and reconstructions proposed by various authors.

The palmar approach for SL ligament repair (Conyers’ technique) is performed through a carpal tunnel incision. A probe or needle passed dorsal to palmar is helpful in locating the ligament tear and palmar ligament intervals. Flaps of radioscaphocapitate and radioscapholunate ligaments are reflected laterally and medially. Palmar cortical bone is removed from the capitate, distal radius, scaphoid, and lunate on either side of the scapholunate interval and the cartilage surfaces of the scaphoid and lunate are denuded to subchondral bone to encourage a strong syndesmosis. The scaphoid and lunate are then reduced and pinned with wires that are left in place for at least 8 to 10 weeks. The palmar ligaments are carefully repaired by overlapping the edges over the denuded cortical bone to ensure healing. Motion is delayed 10 to 12 weeks to encourage adequate strength of the syndesmosis. 

Several procedures have been designed to restrict rotatory subluxation of the scaphoid by creating a dorsal tether. A commonly used method of dorsal capsulodesis is Blatt’s type of capsular reconstruction. Results of Blatt’s capsulodesis for chronic SLD are acceptable, although some clinical series have not reported favorable outcomes that could be a consequence of patient selection. Both short- and longer-term series have reported promising results with the use of a dorsal intercarpal ligament capsulodesis, which is a soft tissue reconstruction procedure based on the dorsal intercarpal ligament of the wrist. The theoretical advantage of this method is that it avoids a tether between the distal radius and scaphoid, allowing the proximal carpal row to work as a functional unit. Wyrick et al. assessed the use of ligament repair and dorsal capsulodesis for static SLD and found that no patients were free of pain at follow-up. Their experience, along with others, has suggested that dorsal capsulodesis is likely more suited to patients with dynamic instability in combination with another procedure rather than for those with static instability. Static instability requires an intercarpal fusion. 

Of the partial wrist fusions performed for wrist instability, the scaphotrapeziotrapezoidal (STT) fusion is frequently recommended in the literature. The purpose of this procedure is to stabilize the distal scaphoid and thereby hold the proximal pole more securely within the scaphoid fossa of the distal radius. An SL fusion has also been described although limited bone contact and the stress exerted by the capitate onto the fusion site make this option less reliable. 

Clinical studies have shown that STT fusion is reliable and effective, giving pain relief and reasonable functional results. Similar results have been recently reported for scaphocapitate fusion in the medium term. However, in the longer term, degenerative changes in adjacent joints may be a problem. In addition, as most wrist motion during daily activities utilizes the dart-throwing mechanism, an RSL fusion with distal scaphoidectomy, and triquetral excision may be a promising option. This procedure requires a healthy midcarpal joint for success. Conflicting evidence exists regarding the benefits of this technically more challenging procedure over other fusion options. Young, active patients with chronic instability and severe arthritis can be treated with excision of the scaphoid and a four-corner fusion with arthrodesis of the capitate, lunate, hamate, and triquetrum. In severe cases, total wrist fusion is a reliable option for pain relief with a predictable loss of wrist motion. 

STT fusion can be performed through a transverse incision centered over the STT joint or through the universal longitudinal incision. If either STT fusion or the equivalent scaphocapitate fusion is undertaken, it is important to reduce the palmarflexed scaphoid, close the SL interval, and maintain carpal height. The ideal flexion angle of the scaphoid is 45 degrees. Fixation of the STT or scaphocapitate joints is performed with K-wires, screws, or staples. Bone graft from the distal radius or iliac crest is placed between the decorticated distal scaphoid and the proximal surfaces of the trapezium and trapezoid (STT fusion), or between the medial articular surface of the scaphoid and the lateral surface of the capitate (scaphocapitate fusion). Once scaphoid alignment is achieved, cancellous bone graft is inserted, and K-wires are placed to support the fusion area. Prereduction placement of K-wires into the scaphoid facilitates correct orientation after reduction. Immobilization after intercarpal fusion is usually for 8 weeks in a scaphoid cast, followed by a support splint for 4 to 6 weeks. CT scans of the wrist can help determine the degree of consolidation at the fusion site. 

Authors’ Preferred Treatment for Scapholunate Dissociation

Lunotriquetral Dissociation

Introduction to Lunotriquetral Dissociation

Lunotriquetral dissociation (LTD) includes sprains, partial, or complete ligament tears, as well as part of the spectrum of perilunate dislocation, or in association with ulnocarpal impingement and TFCC injuries. Lunotriquetral ligament injuries are less frequent than scapholunate ligament injuries. Although LTD is not associated with the development of degenerative changes in the carpus, it can lead to potentially devastating changes to carpal kinematics, especially if it advances to the stage of a VISI deformity. Even without this progression, the patient with chronic ulnar-sided pain experiences significant ongoing disability. 

The mechanism of an isolated LTD is relatively unknown when compared to an LTD injury as part of a perilunate dislocation. The lunotriquetral joint is inherently stable, more so than the scapholunate joint, and it seems that associated ligament damage to the dorsal radiotriquetral ligament or palmar ulnocarpal ligaments must be present before severe fixed deformities occur. 

Assessment of Lunotriquetral Dissociation

Signs and Symptoms

Patients present with a history of injury associated with ulnar-sided wrist pain, worse on activity. Some patients describe a clunking sensation when the wrist moves from radial to ulnar deviation. Clinical signs are often diffuse, although tenderness is often present directly over the lunotriquetral joint, and ballottement of the unstable triquetrum may be possible. Stress provocation tests of the joint including compression, ballottement, or shear may be present, with the most sensitive test to diagnose LTD the lunotriquetral shear test. 

Imaging

Primary assessment uses standard scaphoid radiographs; however, one of the major issues with diagnosing LTD is that many patients have a normal radiograph, with findings often subtle and dynamic, although stress-induced deformity is less frequent than with SLD. The following may be found with an LTD: 

• Disruption of Gilula’s lines on the PA view indicative of an altered intercarpal relationship
• A static VISI deformity on the lateral view (Fig. 43-41)
   

  Figure 43-41

  A VISI deformity of the left wrist.

  

  Figure 43-41

  A VISI deformity of the left wrist.

  

  X
• Associated fractures, for example, a hamate fracture

A VISI deformity of the left wrist. Subsequent MRI confirmed LTD.

Secondary imaging modalities may be required. Wrist arthrography is not a reliable diagnostic tool, but videofluoroscopy can be helpful. Arthroscopy has become the most important diagnostic tool for confirming the presence and degree of LTD, with views of the radiocarpal and midcarpal joints allowing visualization of the scaphoid–trapezoid–trapezium joint, midcarpal extrinsic ligaments, the capitohamate joint, and the articular surfaces of the carpal bones. Arthroscopic staging is applicable to SLD, LTD, and all other ligamentous dissociations. 

Treatment of Lunotriquetral Dissociation

Acute LTD with minimal deformity is ideally treated with a below-elbow cast. If conservative measures fail, surgical intervention should be considered. Little evidence exists supporting the success or failure of conservative treatment modalities. Closed reduction and percutaneous internal fixation of the lunate to the triquetrum is indicated when there is displacement. Arthroscopy can be helpful in acute injuries to guide closed reduction and percutaneous pinning with some suggesting the arthroscope be placed in the radial midcarpal portal for this procedure because the alignment of the LT joint is much easier to evaluate. Arthroscopic debridement with electrothermal treatment may also be beneficial. Ligament repair or reconstruction is also possible with an open repair. 

Indications for open surgery include failure of closed reduction with or without arthroscopy, when the LTD is associated with an angular deformity, or following unsatisfactory results from a previous treatment. An open repair should be attempted only when there are sufficiently strong ligament remnants present, when the ligament remnants have a reasonable healing potential, and when the LT relationship is easily reduced. Good-to-excellent results of open treatment have been reported in 50% to 87% of cases, although the literature in this area is sparse. A recent review suggested a higher rate of reoperation for LT ligament repair compared to reconstruction. 

Open reduction, repair of lax or damaged ligaments, and temporary internal fixation with percutaneous wires across the triquetrum and lunate left in place for 6 to 8 weeks is recommended. All ligaments that seem to be concerned with LT stability should be reattached and it is mandatory to correct any VISI deformity. The interosseous ligament repair is usually done through a dorsal approach. Care should be taken to avoid injury to the dorsal sensory branch of the ulnar nerve. The fifth extensor compartment is opened and an ulnar-based retinacular flap is elevated. The ligament is more likely to be stripped from the triquetrum. Intraosseous bone anchors with attached sutures are used for reconstruction. Capsular flaps are useful for reinforcing the dorsal portion of such a repair or augmenting the dorsal radiotriquetral and dorsal scaphotriquetral ligaments. For late presentations with complete ligament disruption and no tissue for repair, ligament reconstruction using part of the extensor carpi ulnaris tendon is recommended. 

In cases of recurrence and/or when soft tissue repair cannot control recurrent deformity, lunotriquetral joint fusion may be indicated, with or without accompanying denervation procedures. Concomitant ulnar shortening procedures should be considered (especially with ulna plus variance) to tighten the palmar ulnocarpal ligaments in addition to fusion or ligament reconstruction. More aggressive treatments are proximal row carpectomy and total wrist arthrodesis in patients with radiologic signs of arthrosis (Fig. 43-42). 

A, B: Intraoperative images demonstrate osteophyte formation at the LT articular surface. There was instability of the LT articulation with nearly complete cartilage loss at the LT joint. C: A dorsal distal radial bone graft was taken, and an LT fusion was performed with a headless compression screw.

Perilunate Dislocation and Fracture–Dislocation

Introduction to Perilunate Dislocation and Fracture–Dislocation

Perilunate dislocations and fracture–dislocations are the most common forms of wrist dislocation and encompass a spectrum of injuries, which can include both ligamentous and osseous disruption. In clinical practice, the prefix trans is commonly used to refer to associated fractures, whereas the prefix peri- is used to describe a dislocation. Perilunate fracture–dislocations (greater arc injuries) are more frequently seen than perilunate dislocations (lesser arc injuries) with the ratio reported to be two to one, with displacement in a dorsal direction in 97% of cases. The injury is frequently seen in young males with strong bones as the distal radius and the scaphoid need to be strong enough to resist the amount of torque that results in a perilunate dislocation. Prompt management improves the chance of a good long-term outcome; however, all patients should be advised regarding the severity of these injuries and the guarded prognosis. Late diagnosis delays treatment, which is difficult and frequently less successful. Approximately 20% of patients are misdiagnosed at presentation and that delay between injury and treatment worsens the prognosis with neglected cases resulting in pain, weakness, stiffness, carpal tunnel syndrome, and posttraumatic osteoarthritis. 

Perilunate Dislocations

Perilunate dislocations (lesser arc injury) are characterized by a progressive disruption of capsular and ligamentous connections of the lunate to the adjacent carpal bones and radius, without associated fractures to the carpus and distal radius. Ligament disruption typically begins radially and propagates around or through the lunate to the ulnar side of the carpus (Fig. 43-43). Classically, the distal row dislocates in a dorsal or dorsoradial direction followed by the entire scaphoid and triquetrum in pure perilunate dislocations or just by the distal portion of these bones in perilunate fracture–dislocations. SLD or LTD often persists even after relocation, with recurrence of instability common whether the injury involves one or both of the lesser or greater arc. It is important to define any associated ligamentous injuries such as lunotriquetral or SLD to prevent late carpal collapse. For the detailed pathoanatomy of injury please see pages 1602–1604. 

Different types of perilunate dislocations and fracture–dislocations.

Perilunate Fracture–Dislocations

Perilunate fracture–dislocations (greater arc injury) combine ligament ruptures, osseous avulsions, and various types of fractures (Fig. 43-44). The most common pattern of perilunate instability is the transscaphoid perilunate fracture–dislocation. Fractures of the capitate, hamate, lunate, triquetrum, and radial styloids can also occur. In a series of 166 perilunate dislocations and fracture–dislocations, fracture–dislocations were twice as common as a pure dislocation, with 61% being dorsal transscaphoid perilunate fracture–dislocations. Displaced transverse fractures of the neck of the capitate and sagittal fractures of the triquetrum are also quite frequent. The capitate fragment is frequently rotated through 180 degrees so that its articular surface faces the raw cancellous surface of the major capitate fragment. Both capitate and scaphoid fragments are devascularized by displacement, and this is known as the scaphocapitate syndrome. 

A, B: Radiographs of a transradial styloid perilunate dislocation. A fracture of the radial styloid is associated with carpal disruption C, D: Fixation performed with stabilization of the styloid and K-wiring of the carpus in a reduced position.

Assessment of Perilunate Dislocation and Fracture–Dislocation

Signs and Symptoms

Patients are often young males who present following a high-energy (e.g. fall from height, motor-vehicle accident, sports) hyperextension injury, with persistent wrist pain, swelling, and deformity. Approximately a quarter of presentations will be associated with a polytrauma, with 1 in 10 sustaining an associated upper-limb injury. In around 16% of cases, the clinical presentation includes median nerve symptoms and signs, but an ulnar neuropathy, arterial injury, or tendon disruption may also be seen. 

Some perilunate dislocations may be seen several months or years after the initial injury. The patient is more likely to present because of increasing nerve symptoms or tendon rupture than because of wrist deformity to which the patient has often become accustomed. 

Imaging

Primary assessment uses standard scaphoid radiographs with the following appearances suggestive of a perilunate dislocation,: 

• Disruption of Gilula’s lines on the PA view indicative of an altered intercarpal relationship (Fig. 43-45)
   

  Figure 43-45

  Wrist radiographs demonstrating typical radiologic signs of perilunate fracture–dislocation.

  

  Figure 43-45

  Wrist radiographs demonstrating typical radiologic signs of perilunate fracture–dislocation.

  

  X
• “Spilled teapot sign” on the lateral view due to palmar rotation of the lunate and disruption of the lunate–capitate articulation
• Triangular appearance of lunate secondary to rotation
• Increased ulnocarpal translation
  • Neutral PA and radial deviation radiographs recommended
  • Defined as >50% of lunate uncovering
  • Some suggest this is seen in 80% of perilunate injuries

Wrist radiographs demonstrating typical radiologic signs of perilunate fracture–dislocation.

Subtle signs of disruption may include loss of carpal height and increased intercarpal spaces. It is essential to assess for associated fractures of the carpus and distal radius. The literature suggests that 16% to 25% of perilunate dislocations are missed initially with lesser arc injuries commonly missed because of the lack of an obvious osseous pathology and inexperience of the initial observer. Stress radiographs or an examination under anesthesia (EUA) may be necessary. Often secondary imaging modalities are necessary including CT and MRI, with arthrography and arthroscopy useful in determining the extent of the injury. 

Classification

The most frequent systems for describing perilunate injuries include the Mayfield classification (see Fig. 43-10), and the greater or lesser arc injury patterns. Injuries can also be classified as acute or chronic, and reducible or irreducible. The pattern of skeletal deformity is variable. The hand and distal carpal row usually remain intact, but the disruption pattern between distal and proximal carpal rows is quite variable. In the transscaphoid fracture–dislocation, the distal scaphoid dislocates with the distal row leaving the proximal scaphoid and lunate in near-normal relationship to the forearm. When the perilunate ligaments rupture, the lunate usually remains within the radiocarpal joint and the remainder of the carpus dislocates, usually dorsally but occasionally in a volar direction. Occasionally, the lunate is displaced and rotated palmarly and the remainder of the carpus settles into a seminormal alignment with the distal radius. Rarely, even the palmar attachment of the lunate is torn, allowing extrusion into the forearm or through the skin. 

An alternate classification system was put forward by Witvoet and Allieu: 

• Grade I: lunate appears normally aligned
• Grade II: lunate rotated palmarly <90 degrees
• Grade III: lunate rotated palmarly >90 degrees but still attached to the radius by its palmar ligaments
• Grade IV: lunate totally enucleated without any connection to the radius

Herzberg et al. suggested a three-stage classification: 

• Stage I: Dorsal dislocation of capitate, lunate remains in fossa
• Stage IIA: Dorsal dislocation of capitate, lunate dislocated from fossa, rotated <90 degrees
• Stage IIB: Dorsal dislocation of capitate, lunate dislocated from fossa, rotated >90 degrees

Treatment of Perilunate Dislocation and Fracture–Dislocation

Nonoperative management and delayed intervention of perilunate dislocations and fracture–dislocations have been shown to give poor results. Early reduction and operative stabilization is now recommended for most, if not all, cases. However, patients need to be warned regarding the severity of this injury, and the prognosis must always be guarded. Poor prognostic indicators have been found to be manual workers, a poor initial reduction, or those patients managed with a combined volar–dorsal surgical approach. 

Prompt reduction reduces swelling, as well as potential damage to the median nerve. The earlier a reduction of a perilunate dislocation is performed, the easier it is. Ideally, reduction should be undertaken in the emergency room. Complete relaxation under general or regional anesthesia is required, with local anesthesia usually not sufficient. The most commonly used method of closed reduction is the Tavernier maneuver. It consists of locking the capitate into the distal concavity of the lunate by combined axial traction and flexion of the distal row, followed by reduction of the capitate–lunate unit onto the radius by an extension movement, while externally applying a localized, dorsally directed force to the lunate to help reposition it. When the injury cannot be reduced or closed, urgent reduction in theatre is required. Postreduction radiographs are essential to assess the quality of the reduction and the presence of any concomitant fractures that may not have been apparent on initial radiographs. 

Immediate closed reduction reduces any potential pressure on the median nerve, with the majority of patients experiencing resolution of their symptoms after closed reduction. Immediate median nerve decompression is not usually required but should be performed where there is no resolution of symptoms or when late symptoms develop. Severe or increasing median or ulnar neuropathy is always an indication for surgical exploration. 

Surgery can be performed through either a dorsal or volar approach, although a combined approach may be necessary especially if the dislocation is irreducible closed. Some authors use a combined approach in all cases in order to repair the palmar capsule. The dorsal midline approach allows good exposure of the proximal carpal row and midcarpal joint (Fig. 43-46). If there are neurovascular problems, an additional palmar approach allows access for median nerve decompression or repair, vascular repair if required, and repair of the damaged palmar carpal ligaments. This allows both intra-articular and extra-articular damage to be assessed and treated adequately. Some studies have suggested that a combined approach can lead to complications (e.g. wound infection, flexor tendon adhesions) and inferior functional results; however, most authors acknowledge that a combined approach is routinely employed for more severe injuries that are associated with a difficult reduction and/or median nerve symptoms. More recently, minimally invasive and arthroscopy-assisted techniques have been described, reporting comparable or improved outcomes when compared to traditional open approaches. 

A, B: A lunate fracture dislocation on radiographs and CT. C, D: Stabilization was performed with retrograde screw fixation of the scaphoid, with reduction and percutaneous pinning performed under direct control. Additional K-wires can be inserted into the scaphoid and lunate to help with the reduction.

Lesser-Arc Injuries

There are reductions that are so stable that it is difficult to determine whether a full perilunate-type dislocation took place, and there are others that reduce and can be maintained in near-normal alignment with cast immobilization. Successful closed reduction requires adequate imaging with good standardized AP and lateral radiographs of the wrist. Inadequate reduction leads to a poor prognosis. It is important to confirm any ligamentous stability with stress-test radiographs, MRI, arthroscopy, or open exploration. The very rare injury that reduces to normal alignment by closed reduction and appears stable can be treated with a scaphoid cast with the wrist in a neutral position. Many authors advocate daily review in the first week to ensure there is no redisplacement. Adkison and Chapman reported loss of reduction over time after anatomic realignment in 59% of patients treated with immobilization. Review should then take place every week up until 12 weeks when the cast can be removed. 

However, the results of closed reduction and cast immobilization are unpredictable with loss of reduction common with one study finding that carpal instability persisted despite 17 weeks of casting. It is now generally agreed that the risk of late deformity after successful reduction and cast management alone is unacceptably high and many advocate early operative intervention. The use of percutaneous K-wire fixation to stabilize the carpus after closed reduction is now recommended. This reduces the incidence of late loss of reduction and enhances the healing capability of the intrinsic ligaments. If possible, pin fixation can be performed using arthroscopy. Perilunate dislocations that are stable after reduction require only two pins for fixation. One transverse pin is placed from the scaphoid into the lunate (this can also be pinned through the radius into the lunate to neutralize the radiolunate alignment), and a second pin is placed from the scaphoid into the capitate. Pin stabilization of the lunotriquetral articulation is debated. The pins are usually removed at 8 weeks, but wrist immobilization in a scaphoid cast should be maintained for a total of 12 weeks after reduction. 

Most perilunate dislocations fall into the irreducible or unstable group. If reduction is not optimal or reduction cannot be achieved at all, then open exploration and repair is indicated. Significantly better results have been reported after open reduction, ligament repair, and K-wire stabilization compared with closed reduction and percutaneous pinning. Some authors advocate the use of temporary screw fixation as opposed to K-wires to facilitate early motion. 

The prognosis for these injuries is guarded even with successful reduction and maintenance of intercarpal stability, with longer-term studies reporting good patient satisfaction, but with high rates of loss of reduction and arthrosis although this does not correlate with the outcome. In a midterm study of 22 patients with perilunate dislocations treated with open reduction, cerclage wire fixation, and ligament repair, patient satisfaction was high for 15 patients, the range of movement was 87%, and grip strength 77% of the contralateral wrist, but only 10 patients returned to the same type of employment as before their injury. 

Greater-Arc Injuries

Treatment is by immediate closed reduction followed by open reduction and internal fixation, which is the best method of achieving anatomic reduction of the fracture fragments. This also allows repair of associated ligament injuries, as well as primary bone grafting when there is comminution of the scaphoid. Cannulated screw fixation of the scaphoid is routinely recommended although there are some reports of K-wire fixation alone. Again, stabilization of the lunotriquetral articulation is debated. 

Most series report acceptable radiologic results, although the majority of cases have radiographic arthritis at longer-term review that does not seem to correlate with the outcome. The incidence of posttraumatic arthrosis ranges from 7% to 92% with a mean of 38%. Overall patient satisfaction is reported to be satisfactory with return to employment, although restoration of function is rarely complete with residual wrist stiffness and weakness of grip strength documented. 

Chronic Perilunate Dislocations

Those injuries seen within 3 months are still potentially treatable by open reduction as long as no cartilage degeneration has already occurred, although treatment at this stage is often more difficult because of articular changes and capsular contracture, leading to inferior outcomes. Some advocate that open reduction and internal fixation should not be attempted beyond 6 weeks from injury. A good clue to the potential success of late reduction is gained by examining radiographs of the carpus under 25 to 30 lb of traction. An attempt at open reduction (by palmar and dorsal approaches), repair, and internal fixation should be offered if carpal bone realignment is feasible, because even in late cases results can be surprisingly good. Kailu et al. recently reported outcomes in 10 patients treated with open reduction and internal fixation after a delayed or chronic presentation. Patient-rated clinical scores demonstrated good outcomes in most patients. Radiographic measurements remained in the normal range at final follow-up (90 months). 

Late problems such as carpal bone ischemia and ligament contracture nearly always require some type of salvage operation, such as a proximal row carpectomy or a total wrist arthrodesis. Proximal row carpectomy usually provides satisfactory results when the capitate head and lunate fossa are preserved. 

Some patients undergo unsuccessful acute management. Depending on the time of presentation from injury and the extent and type of any surgery that has already been undertaken, the options for treatment are identical to those of acute treatment. When a bone or bone fragment has been removed, such as a proximal scaphoid or capitate fragment, the alternatives are to rehabilitate the limb and assess the functional level or to consider a salvage procedure such as radiocarpal fusion or proximal row carpectomy. 

Authors’ Preferred Treatment for Perilunate Dislocation and Fracture–Dislocations (Algorithm 43-2)

Authors’ preferred treatment for perilunate dislocations.

Radiocarpal Instability

Introduction to Radiocarpal Instability

The most common injuries at the radiocarpal joint are fracture–dislocations of the distal radius and carpus, such as palmar and dorsal Barton fracture–dislocations, radial styloid fracture–dislocations, and die-punch fracture–dislocations. Less common are the pure ligamentous radiocarpal injuries that may result in a true ulnar, dorsal, or palmar dislocation of the wrist, with some missed as they may spontaneously reduce (Fig. 43-47). Ulnar translation is the most frequent radiocarpal instability. These injuries occur predominantly in young males and are often severe in nature. 

Radiocarpal dislocation with torn radiocarpal ligaments. This injury requires K-wire stabilization and direct repair of the radiocarpal ligaments.

Assessment of Radiocarpal Instability

Signs and Symptoms

Radiocarpal instability may occur acutely, develop gradually, or be observed as a late sequela of a perilunate dislocation. In the acute phase, patients present with a history of high-energy trauma, such as a fall from height. They complain frequently of wrist swelling, deformity, and pain. Dorsal wrist swelling and tenderness are most noticeable at the radiocarpal level and are aggravated by wrist motion. Deformity may be due to an ulnar, dorsal, or palmar translation of the carpus. With ulnar translation, the wrist and hand are offset in an ulnar direction. Most patients sustain an associated injury, with disruption to the ipsilateral distal radioulnar joint common, and thorough assessment is recommended. 

Imaging

Primary assessment uses standard scaphoid radiographs to detect displacement and associated fractures. Provocative stress tests may be required to demonstrate dynamic radiocarpal instability. In those patients with an ulnar translation, the radiographic appearance is often dramatic with the lunate positioned just distal to the ulna and a large space between the radial styloid and the scaphoid. If a perilunate injury is also present the lunate and triquetrum slide ulnarly, opening a gap between the scaphoid and lunate. In some cases, the ulnar shift is subtle, and a decrease in the ulnocarpal index may provide the only clue to diagnosis. Chronic causes for ulnar translation include rheumatoid arthritis and in developmental deformities (e.g. Madelung deformity). 

To better define associated bony injuries, CT may be required. To determine the extent of ligamentous disruption, MRI can be used. 

Classification

Radiocarpal dislocation has been classified into two groups by Dumontier et al.: 

• Type I: Radiocarpal dislocation with no fracture, or a fracture of the tip of the radial styloid, when it is assumed that the radiocarpal ligaments are avulsed from the radius
• Type II: Radiocarpal dislocation with a fracture of the radial styloid involving more than one third of the scaphoid fossa, when it is assumed that the radiocarpal ligaments remain attached to the styloid process

Moneim also classified these injuries into two groups, but his classification is dependent on the presence or absence of intercarpal ligament injury: 

• Type I: Intact intercarpal ligaments
• Type II: A combination of radiocarpal and intercarpal dislocation

Dorsal translation of the carpus together with ulnar translation can be seen in two modes: one a true instability secondary to ligament damage, the other an apparent instability due to a carpal shift in response to a change in position of the distal radial articular surface. Pure dorsal translation usually occurs after a loss of the normal palmar slope of the distal radius from a flexion angle to an extension angle. The latter is a common problem after collapse of a distal radius fracture. 

Treatment of Radiocarpal Instability

Dislocations of the radiocarpal joint require immediate reduction because the associated deformity may compromise adjacent neurovascular structures. Although reduction is usually possible, maintaining it is often difficult. Open treatment should be considered in most carpal dislocations. 

For type I injuries, the volar radiocarpal ligaments should be repaired using anchor sutures to prevent secondary ulnar or volar translation. Where there is a substantial fracture fragment, the volar ligaments are likely to be attached to it, therefore, ORIF of the fragment is necessary. Added stabilization of the radiocarpal joint is recommended using percutaneous K-wires or external fixation to prevent late carpal translation, especially in type I injuries. Concomitant intercarpal ligament injuries should also be repaired. Limitation of wrist movement of 30% to 40% of normal should be expected following radiocarpal dislocation. 

The use of a wrist spanning bridge plate has also been described. This technique supports and protects the ligamentous repair and may prove easier with higher patient acceptance. Rubensson et al. recently published their results of radioscaphocapitate and long radiolunate ligament tensioning in patients with posttraumatic radiocarpal instability. Long-term outcomes were available in 14 patients demonstrating markedly improved symptoms in all, with 4 patients symptom-free. The authors hypothesized that tensioning the volar ligaments closed the space of Poirier and improved stability. In contrast, a very recent retrospective study examined the outcomes in 41 patients treated for radiocarpal dislocation and fracture–dislocations. Six of the original 41 patients required a secondary wrist fusion. Overall, functional outcomes were good with QuickDASH and PWRE scores of 23 and 27, respectively. The authors concluded that in the setting of a concentric anatomic reduction confirmed through a dorsal approach no additional volar ligament or capsule repair was required. Unfortunately, limited evidence exists to guide our treatment of these injuries. 

For those with a delayed presentation or diagnosis, ligamentous repair does not usually provide a good result. The most certain method of controlling possible recurrence of deformity is to carry out a partial or total radiocarpal arthrodesis. Radiolunate fusion is an appropriate technique for this situation, although the variation of joint damage may indicate radioscaphoid fusion in some cases and radioscapholunate fusion in others. The latter is usually indicated in the combination of radiocarpal and perilunate instability. 

Future Directions Related to Carpal Ligament Injuries

We still need more short- and long-term outcome data for all the carpal instabilities. Substantial progress continues to be made in the understanding and detection of carpal ligament injuries, predominantly due to the ever-improving imaging modalities available. Hopefully, improved imaging and surgery will allow better prediction of the evolution of individual carpal instabilities and therefore determine the requirement for operative treatment at an earlier stage. It is likely that improved surgical methods will be devised to treat these problems. The use of closed fluoroscopically or arthroscopically controlled techniques is increasing, but whether the results of treatment are improving is still debated. 

It is interesting to speculate whether an increasingly aging society will affect the diagnosis and management of both carpal fractures and instabilities. Currently, they mainly occur in younger patients, but with altering patient demographics, this may not continue, and a new set of challenges may emerge. 

Carpal Ligament Injuries: Pearls and Pitfalls

• SLD is the most common pattern of carpal instability.
• SLD without a dorsiflexed lunate is probably not traumatic.
• For SLD, the results of K-wire treatment are unpredictable and ligamentous repair should be undertaken if closed reduction is unsuccessful on serial radiographs.
• For chronic scapholunate instability, partial or complete wrist fusion may be needed.
• Perilunate dislocation patterns include a considerable spectrum of sprains, fracture–dislocations and instabilities.
• Up to a quarter of perilunate dislocations are initially missed.
• Perilunate dislocation and fracture–dislocations routinely require immediate reduction and operative stabilization.
• LTD may result in disruption of Gilula’s lines on the radiograph.
• Open repair of the lunotriquetral ligament is possible only in acute injury.

Annotated References

References

• 1 Abdel-Salam A, Eyres KS, Cleary J. Detecting fractures of the scaphoid: the value of comparative x-rays of the uninjured wrist. J Hand Surg Br. 1992;17:28–32.
• 2 Adamany DC, Mikola EA, Fraser BJ. Percutaneous fixation of the scaphoid through a dorsal approach: an anatomic study. J Hand Surg Am. 2008;33:327–331.
• 3 Adey L, Souer JS, Lozano-Calderon S, et al. Computed tomography of suspected scaphoid fractures. J Hand Surg Am. 2007;32:61–66.
• 4 Adkison JW, Chapman MW. Treatment of acute lunate and perilunate dislocations. Clin Orthop Relat Res. 1982;164:199–207.
• 5 Adler BD, Logan PM, Janzen DL, et al. Extrinsic radiocarpal ligaments: magnetic resonance imaging of normal wrists and scapholunate dissociation. Can Assoc Radiol J. 1996;47:417–422.
• 6 Adolfsson L, Lindau T, Arner M. Acutrak screw fixation versus cast immobilization for undisplaced scaphoid waist fractures. J Hand Surg Br. 2001;26:192–195.
• 7 Aguilella L, Garcia-Elias M. The anterolateral corner of the radial metaphysis as a source of bone graft for the treatment of scaphoid nonunion. J Hand Surg Am. 2012;37:1258–1262.
• 8 Aibinder WR, Wagner ER, Bishop AT, et al. Bone grafting for scaphoid nonunions: is free vascularized bone grafting superior for scaphoid nonunion? Hand (NY). 2017;1558944717736397.
• 9 Al-Ajmi TA, Al-Faryan KH, Al-Kanaan NF, et al. A systematic review and meta-analysis of randomized controlled trials comparing surgical versus conservative treatments for acute undisplaced or minimally-displaced scaphoid fractures. Clin Orthop Surg. 2018;10:64–73.
• 10 Albertsen J, Mencke S, Christensen L, et al. Isolated capitate fracture diagnosed by computed tomography. Case report. Handchir Mikrochir Plast Chir. 1999;31:79–81.
• 11 Aldridge JM3rd, Mallon WJ. Hook of the hamate fractures in competitive golfers: results of treatment by excision of the fractured hook of the hamate. Orthopedics. 2003;26:717–719.
• 12 Alho A, Kankaanpää. Management of fractured scaphoid bone: a prospective study of 100 fractures. Acta Orthop Scand. 1975;46:737–743.
• 13 Allan CH, Joshi A, Lichtman DM. Kienböck’s disease: diagnosis and treatment. J Am Acad Orthop Surg. 2001;9:128–136.
• 14 Almquist EE, Bach AW, Sack JT, et al. Four-bone ligament reconstruction for treatment of chronic complete scapholunate separation. J Hand Surg Am. 1991;16:322–327.
• 15 Alnaeem H, Aldekhayel S, Kanevsky J, et al. A systematic review and meta-analysis examining the differences between nonsurgical management and percutaneous fixation of minimally and nondisplaced scaphoid fractures. J Hand Surg Am. 2016;41:1135–1144.
• 16 Alonso Rasgado T, Zhang Q, Jimenez Cruz D, et al. Analysis of tenodesis techniques for treatment of scapholunate instability using the finite element method. Int J Numer Method Biomed Eng. 2017;33.
• 17 Alshryda S, Shah A, Odak S, et al. Acute fractures of the scaphoid bone: systematic review and meta-analysis. Surgeon. 2012;10(4):218–229.
• 18 Alt V, Sicre G. Dorsal transscaphoid-transtriquetral perilunate dislocation in pseudarthrosis of the scaphoid. Clin Orthop Relat Res. 2004;135–137.
• 19 Altissimi M, Mancini GB, Azzara A. Perilunate dislocations of the carpus. A long-term review. Ital J Orthop Traumatol. 1987;13:491–500.
• 20 Altman DG, Bland JM. Diagnostic tests. 1: Sensitivity and specificity. BMJ. 1994;308:1552.
• 21 Altman DG, Bland JM. Diagnostic tests. 2: Predictive values. BMJ. 1994;309:102.
• 22 Amadio PC, Berquist TH, Smith DK, et al. Scaphoid malunion. J Hand Surg Am. 1989;14:679–687.
• 23 American College of Radiology (ACR). Expert panel on musculoskeletal imaging, ACR appropriateness criteria. In: Acute Hand and Wrist Trauma. Reston, VA: American College of Radiology; 2001:1–7.
• 24 Amirfeyz R, Bebbington A, Downing ND, et al. Displaced scaphoid waist fractures: the use of a week 4 CT scan to predict the likelihood of union with nonoperative treatment. J Hand Surg Eur Vol. 2011;36:498–502.
• 25 Anderson ML, Skinner JA, Felmlee JP, et al. Diagnostic comparison of 1.5 Tesla and 3.0 Tesla preoperative MRI of the wrist in patients with ulnar-sided wrist pain. J Hand Surg Am. 2008;33:1153–1159.
• 26 Anderson SE, Steinbach LS, Tschering-Vogel D, et al. MR imaging of avascular scaphoid nonunion before and after vascularized bone grafting. Skeletal Radiol. 2005;34:314–320.
• 27 Andresen R, Radmer S, Sparmann M, et al. Imaging of hamate bone fractures in conventional x-rays and high-resolution computed tomography. An in vitro study. Invest Radiol. 1999;34:46–50.
• 28 Annamalai G, Raby N. Scaphoid and pronator fat stripes are unreliable soft tissue signs in the detection of radiographically occult fractures. Clin Radiol. 2003;58:798–800.
• 29 Apergis E, Darmanis S, Kastanis G, et al. Does the term scaphocapitate syndrome need to be revised? A report of 6 cases. J Hand Surg Br. 2001;26:441–445.
• 30 Apergis E, Maris J, Theodoratos G, et al. Perilunate dislocations and fracture-dislocations: closed and early open reduction compared in 28 cases. Acta Orthop Scand Suppl. 1997;275:55–59.
• 31 Apostolides JG, Lifchez SD, Christy MR. Complex and rare fracture patterns in perilunate dislocations. Hand (NY). 2011;6:287–294.
• 32 Arner M, Hagberg L. Wrist flexion strength after excision of the pisiform bone. Scand J Plast Reconstr Surg. 1984;18:241–245.
• 33 Arora R, Gschwentner M, Krappinger D, et al. Fixation of nondisplaced scaphoid fractures: making treatment cost effective. Prospective controlled trial. Arch Orthop Trauma Surg. 2007;127:39–46.
• 34 Arora R, Lutz M, Zimmermann R, et al. Free vascularised iliac bone graft for recalcitrant avascular nonunion of the scaphoid. J Bone Joint Surg Br. 2010;92:224–229.
• 35 Atkinson CT, Watson J. Lunotriquetral ligament tears. J Hand Surg Am. 2012;37:2142–2144.
• 36 Baczkowski B, Lorczynski A, Kabula J, et al. Scapholunate ligament repair using suture anchors. Ortop Traumatol Rehabil. 2006;8:129–133.
• 37 Bain GI, Bennett JD, MacDermid JC, et al. Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques. J Hand Surg Am. 1998;23:76–81.
• 38 Bain GI, Ondimu P, Hallam P, et al. Radioscapholunate arthrodesis—a prospective study. Hand Surg. 2009;14:73–82.
• 39 Bain GI, Sood A, Yeo CJ. RSL fusion with excision of distal scaphoid and triquetrum: a cadaveric study. J Wrist Surg. 2014;3:37–41.
• 40 Bain GI, Turow A, Phadnis J. Dorsal plating of unstable scaphoid fractures and nonunions. Tech Hand Up Extrem Surg. 2015;19:95–100.
• 41 Barcia AM, Zhou L, Cook JB, et al. Digital tomography for detection of acute occult scaphoid fractures. Orthopedics. 2017;40:e1092–e1095.
• 42 Barton NJ. Twenty questions about scaphoid fractures. J Hand Surg Br. 1992;17:289–310.
• 43 Beadel GP, Ferreira L, Johnson JA, et al. Interfragmentary compression across a simulated scaphoid fracture—analysis of 3 screws. J Hand Surg Am. 2004;29:273–278.
• 44 Becce F, Theumann N, Bollmann C, et al. Dorsal fractures of the triquetrum: MRI findings with an emphasis on dorsal carpal ligament injuries. AJR Am J Roentgenol. 2013;200:608–617.
• 45 Beckenbaugh RD, Shives TC, Dobyns JH, et al. Kienböck’s disease: the natural history of Kienböck’s disease and consideration of lunate fractures. Clin Orthop Relat Res. 1980;98–106.
• 46 Beeres FJ, Hogervorst M, Rhemrev SJ, et al. A prospective comparison for suspected scaphoid fractures: bone scintigraphy versus clinical outcome. Injury. 2007;38:769–774.
• 47 Beeres FJ, Rhemrev SJ, den Hollander P, et al. Early magnetic resonance imaging compared with bone scintigraphy in suspected scaphoid fractures. J Bone Joint Surg Br. 2008;90:1205–1209.
• 48 Beredjiklian PK, Dugas J, Gerwin M. Primary repair of the scapholunate ligament. Tech Hand Up Extrem Surg. 1998;2:269–273.
• 49 Berger RA. The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg Am. 1996;21:170–178.
• 50 Berger RA. The ligaments of the wrist. A current overview of anatomy with considerations of their potential functions. Hand Clin. 1997;13:63–82.
• 51 Berger RA. The anatomy of the ligaments of the wrist and distal radioulnar joints. Clin Orthop Relat Res. 2001;32–40.
• 52 Berger RA. The anatomy of the scaphoid. Hand Clin. 2001;17:525–532.
• 53 Berger RA, Blair WF, Crowninshield RD, et al. The scapholunate ligament. J Hand Surg Am. 1982;7:87–91.
• 54 Berger RA, Blair WF, El-Khoury GY. Arthrotomography of the wrist. The palmar radiocarpal ligaments. Clin Orthop Relat Res. 1984;224–229.
• 55 Berger RA, Imeada T, Berglund L, et al. Constraint and material properties of the subregions of the scapholunate interosseous ligament. J Hand Surg Am. 1999;24:953–962.
• 56 Berger RA, Landsmeer JM. The palmar radiocarpal ligaments: a study of adult and fetal human wrist joints. J Hand Surg Am. 1990;15:847–854.
• 57 Bergh TH, Lindau T, Soldal LA, et al. Clinical scaphoid score (CSS) to identify scaphoid fracture with MRI in patients with normal x-ray after a wrist trauma. Emerg Med J. 2014;31:659–664.
• 58 Bergh TH, Steen K, Lindau T, et al. Costs analysis and comparison of usefulness of acute MRI and 2 weeks of cast immobilization for clinically suspected scaphoid fractures. Acta Orthop. 2015;86:303–309.
• 59 Bernard SA, Murray PM, Heckman MG. Validity of conventional radiography in determining scaphoid waist fracture displacement. J Orthop Trauma. 2010;24:448–451.
• 60 Bettinger PC, Linscheid RL, Berger RA, et al. An anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal joint. J Hand Surg Am. 1999;24:786–798.
• 61 Bhalla S, Higgs PE, Gilula LA. Utility of the radial-deviated, thumb-abducted lateral radiographic view for the diagnosis of hamate hook fractures: case report. Radiology. 1998;209:203–207.
• 62 Bhat M, McCarthy M, Davis TR, et al. MRI and plain radiography in the assessment of displaced fractures of the waist of the carpal scaphoid. J Bone Joint Surg Br. 2004;86:705–713.
• 63 Bickert B, Sauerbier M, Germann G. Scapholunate ligament repair using the Mitek bone anchor. J Hand Surg Br. 2000;25:188–192.
• 64 Blatt G. Capsulodesis in reconstructive hand surgery: dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna. Hand Clin. 1987;3:81–102.
• 65 Blomquist GA, Hunt Iii TR, Lopez-Ben RR. Isolated fractures of the trapezoid as a sports injury. Skeletal Radiol. 2013;42:735–739.
• 66 Boabighi A, Kuhlmann JN, Kenesi C. The distal ligamentous complex of the scaphoid and the scapho-lunate ligament. An anatomic, histological and biomechanical study. J Hand Surg Br. 1993;18:65–69.
• 67 Bohler L, Trojan E, Jahna H. The results of treatment of 734 fresh, simple fractures of the scaphoid. J Hand Surg Br. 2003;28:319–331.
• 68 Bond CD, Shin AY, McBride MT, et al. Percutaneous screw fixation or cast immobilization for nondisplaced scaphoid fractures. J Bone Joint Surg Am. 2001;83-A:483–488.
• 69 Borel C, Larbi A, Delclaux S, et al. Diagnostic value of cone beam computed tomography (CBCT) in occult scaphoid and wrist fractures. Eur J Radiol. 2017;97:59–64.
• 70 Botte MJ, Gelberman RH. Fractures of the carpus, excluding the scaphoid. Hand Clin. 1987;3:149–161.
• 71 Botte MJ, Pacelli LL, Gelberman RH. Vascularity and osteonecrosis of the wrist. Orthop Clin North Am. 2004;35:405–421, xi.
• 72 Boutry N, Lapegue F, Masi L, et al. Ultrasonographic evaluation of normal extrinsic and intrinsic carpal ligaments: preliminary experience. Skeletal Radiol. 2005;34:513–521.
• 73 Braga-Silva J, Peruchi FM, Moschen GM, et al. A comparison of the use of distal radius vascularised bone graft and non-vascularised iliac crest bone graft in the treatment of non-union of scaphoid fractures. J Hand Surg Eur Vol. 2008;33:636–640.
• 74 Braunstein EM, Louis DS, Greene TL, et al. Fluoroscopic and arthrographic evaluation of carpal instability. AJR Am J Roentgenol. 1985;144:1259–1262.
• 75 Breederveld RS, Tuinebreijer WE. Investigation of computed tomographic scan concurrent criterion validity in doubtful scaphoid fracture of the wrist. J Trauma. 2004;57:851–854.
• 76 Breitenseher MJ, Metz VM, Gilula LA, et al. Radiographically occult scaphoid fractures: value of MR imaging in detection. Radiology. 1997;203:245–250.
• 77 Brondum V, Larsen CF, Skov O. Fracture of the carpal scaphoid: frequency and distribution in a well-defined population. Eur J Radiol. 1992;15:118–122.
• 78 Brooks S, Wluka AE, Stuckey S, et al. The management of scaphoid fractures. J Sci Med Sport. 2005;8:181–189.
• 79 Brown RR, Fliszar E, Cotten A, et al. Extrinsic and intrinsic ligaments of the wrist: normal and pathologic anatomy at MR arthrography with three-compartment enhancement. Radiographics. 1998;18:667–674.
• 80 Brumbaugh RB, Crowninshield RD, Blair WF, et al. An in-vivo study of normal wrist kinematics. J Biomech Eng. 1982;104:176–181.
• 81 Brydie A, Raby N. Early MRI in the management of clinical scaphoid fracture. Br J Radiol. 2003;76:296–300.
• 82 Buijze GA, Doornberg JN, Ham JS, et al. Surgical compared with conservative treatment for acute nondisplaced or minimally displaced scaphoid fractures: a systematic review and meta-analysis of randomized controlled trials. J Bone Joint Surg Am. 2010;92:1534–1544.
• 83 Buijze GA, Dvinskikh NA, Strackee SD, et al. Osseous and ligamentous scaphoid anatomy: Part II. Evaluation of ligament morphology using three-dimensional anatomical imaging. J Hand Surg Am. 2011;36:1936–1943.
• 84 Buijze GA, Goslings JC, Rhemrev SJ, et al. Cast immobilization with and without immobilization of the thumb for nondisplaced and minimally displaced scaphoid waist fractures: a multicenter, randomized, controlled trial. J Hand Surg Am. 2014;39:621–627.
• 85 Buijze GA, Guitton TG, van Dijk CN, et al. Training improves interobserver reliability for the diagnosis of scaphoid fracture displacement. Clin Orthop Relat Res. 2012;470(7):2029–2034.
• 86 Buijze GA, Jorgsholm P, Thomsen NO, et al. Diagnostic performance of radiographs and computed tomography for displacement and instability of acute scaphoid waist fractures. J Bone Joint Surg Am. 2012;94(21):1967–1974.
• 87 Buijze GA, Jorgsholm P, Thomsen NO, et al. Factors associated with arthroscopically determined scaphoid fracture displacement and instability. J Hand Surg Am. 2012;37:1405–1410.
• 88 Buijze GA, Lozano-Calderon SA, Strackee SD, et al. Osseous and ligamentous scaphoid anatomy: Part I. A systematic literature review highlighting controversies. J Hand Surg Am. 2011;36:1926–1935.
• 89 Buijze GA, Mallee WH, Beeres FJ, et al. Diagnostic performance tests for suspected scaphoid fractures differ with conventional and latent class analysis. Clin Orthop Relat Res. 2011;469:3400–3407.
• 90 Buijze GA, Ochtman L, Ring D. Management of scaphoid nonunion. J Hand Surg Am. 2012;37:1095–1100.
• 91 Burgess RC. The effect of a simulated scaphoid malunion on wrist motion. J Hand Surg Am. 1987;12:774–776.
• 92 Calandruccio JH, Duncan SF. Isolated nondisplaced capitate waist fracture diagnosed by magnetic resonance imaging. J Hand Surg Am. 1999;24:856–859.
• 93 Calfee RP, White L, Patel A, et al. Palmar dislocation of the trapezoid with coronal shearing fracture: case report. J Hand Surg Am. 2008;33:1482–1485.
• 94 Caloia MF, Gallino RN, Caloia H, et al. Incidence of ligamentous and other injuries associated with scaphoid fractures during arthroscopically assisted reduction and percutaneous fixation. Arthroscopy. 2008;24:754–759.
• 95 Campbell RD Jr, Thompson TC, Lance EM, et al. Indications for open reduction of lunate and perilunate dislocations of the carpal bones. J Bone Joint Surg Am. 1965;47:915–937.
• 96 Camus EJ, Millot F, Lariviere J, et al. The double-cup carpus: a demonstration of the variable geometry of the carpus. Chir Main. 2008;27:12–19.
• 97 Capo JT, Corti SJ, Shamian B, et al. Treatment of dorsal perilunate dislocations and fracture-dislocations using a standardized protocol. Hand (NY). 2012;7:380–387.
• 98 Carratala V, Lucas FJ, Alepuz ES, et al. Arthroscopically assisted ligamentoplasty for axial and dorsal reconstruction of the scapholunate ligament. Arthrosc Tech. 2016;5:e353–e359.
• 99 Carroll RE, Lakin JF. Fracture of the hook of the hamate: acute treatment. J Trauma. 1993;34:803–805.
• 100 Cautilli GP, Wehbe MA. Scapho-lunate distance and cortical ring sign. J Hand Surg Am. 1991;16:501–503.
• 101 Cetti R, Christensen SE, Reuther K. Fracture of the lunate bone. Hand. 1982;14:80–84.
• 102 Chantelot C, Peltier B, Demondion X, et al. A trans STT, trans capitate perilunate dislocation of the carpus. A case report. Ann Chir Main Memb Super. 1999;18:61–65.
• 103 Charalambous CP, Mills SP, Hayton MJ. Gradual distraction using an external fixator followed by open reduction in the treatment of chronic lunate dislocation. Hand Surg. 2010;15:27–29.
• 104 Cheng CY, Hsu KY, Tseng IC, et al. Concurrent scaphoid fracture with scapholunate ligament rupture. Acta Orthop Belg. 2004;70:485–491.
• 105 Chennagiri RJ, Lindau TR. Assessment of scapholunate instability and review of evidence for management in the absence of arthritis. J Hand Surg Eur Vol. 2013;38:727–738.
• 106 Cheung GC, Lever CJ, Morris AD. X-ray diagnosis of acute scaphoid fractures. J Hand Surg Br. 2006;31:104–109.
• 107 Choi R, Raskin KB. Rotatory subluxation of the scaphoid. Bull Hosp Jt Dis. 2000;59:197–200.
• 108 Chou YC, Hsu YH, Cheng CY, et al. Percutaneous screw and axial Kirschner wire fixation for acute transscaphoid perilunate fracture dislocation. J Hand Surg Am. 2012;37(4):715–720.
• 109 Christiansen TG, Rude C, Lauridsen KK, et al. Diagnostic value of ultrasound in scaphoid fractures. Injury. 1991;22:397–399.
• 110 Chung KC. A simplified approach for unstable scaphoid fracture fixation using the Acutrak screw. Plast Reconstr Surg. 2002;110:1697–1703.
• 111 Clark DW, Blackburn N. Treatment of periscaphoid osteoarthritis by Silastic scaphoid implant. J R Soc Med. 1989;82:464–465.
• 112 Clay NR, Dias JJ, Costigan PS, et al. Need the thumb be immobilised in scaphoid fractures? A randomised prospective trial. J Bone Joint Surg Br. 1991;73:828–832.
• 113 Clementson M, Jorgsholm P, Besjakov J, et al. Conservative treatment versus arthroscopic-assisted screw fixation of scaphoid waist fractures–a randomized trial with minimum 4-year follow-up. J Hand Surg Am. 2015;40:1341–1348.
• 114 Clementson M, Jorgsholm P, Besjakov J, et al. Union of scaphoid waist fractures assessed by CT scan. J Wrist Surg. 2015;4:49–55.
• 115 Cohen MS, Jupiter JB, Fallahi K, et al. Scaphoid waist nonunion with humpback deformity treated without structural bone graft. J Hand Surg Am. 2013;38(4):701–705.
• 116 Cohen MS, Taleisnik J. Direct ligamentous repair of scapholunate dissociation with capsulodesis augmentation. Tech Hand Up Extrem Surg. 1998;2:18–24.
• 117 Collins ED, Gharbaoui I. Imaging and anatomic study of the pisiform bone/ulnar nerve relationship-evaluation of the preferred surgical approach for the excision of the pisiform bone. Tech Hand Up Extrem Surg. 2010;14:150–154.
• 118 Compson JP. The anatomy of acute scaphoid fractures: a three-dimensional analysis of patterns. J Bone Joint Surg Br. 1998;80:218–224.
• 119 Compton N, Murphy L, Lyons F, et al. Tomosynthesis: a new radiologic technique for rapid diagnosis of scaphoid fractures. Surgeon. 2018;16:131–136.
• 120 Conyers DJ. Scapholunate interosseous reconstruction and imbrication of palmar ligaments. J Hand Surg Am. 1990;15:690–700.
• 121 Cooney WP. Failure of treatment of ununited fractures of the carpal scaphoid. J Bone Joint Surg Am. 1984;66:1145–1146.
• 122 Cooney WP 3rd. Scaphoid fractures: current treatments and techniques. Instr Course Lect. 2003;52:197–208.
• 123 Cooney AD, Stuart PR. Symptomatic nonunion of an isolated capitate fracture in an adolescent. J Hand Surg Eur Vol. 2013;38(5):565–567.
• 124 Cooney WP, Bussey R, Dobyns JH, et al. Difficult wrist fractures. Perilunate fracture-dislocations of the wrist. Clin Orthop Relat Res. 1987;(214):136–147.
• 125 Cooney WP, Dobyns JH, Linscheid RL. Fractures of the scaphoid: a rational approach to management. Clin Orthop Relat Res. 1980;(149):90–97.
• 126 Cooney WP 3rd, Dobyns JH, Linscheid RL. Nonunion of the scaphoid: analysis of the results from bone grafting. J Hand Surg Am. 1980;5:343–354.
• 127 Cooney WP, Dobyns JH, Linscheid RL. Arthroscopy of the wrist: anatomy and classification of carpal instability. Arthroscopy. 1990;6:133–140.
• 128 Cordrey LJ, Ferrer-Torells M. Management of fractures of the greater multangular. Report of five cases. J Bone Joint Surg Am. 1960;42-A:1111–1118.
• 129 Court-Brown CM, Caesar B. Epidemiology of adult fractures: a review. Injury. 2006;37:691–697.
• 130 Court-Brown CM, Bugler KE, Clement ND, et al. The epidemiology of open fractures in adults. A 15-year review. Injury. 2012;43:891–897.
• 131 Cruickshank J, Meakin A, Breadmore R, et al. Early computerized tomography accurately determines the presence or absence of scaphoid and other fractures. Emerg Med Australas. 2007;19:223–228.
• 132 Dacho A, Grundel J, Holle G, et al. Long-term results of midcarpal arthrodesis in the treatment of scaphoid nonunion advanced collapse (SNAC-wrist) and scapholunate advanced collapse (SLAC-Wrist). Ann Plast Surg. 2006;56:139–144.
• 133 DaCruz DJ, Taylor RH, Savage B, et al. Ultrasound assessment of the suspected scaphoid fracture. Arch Emerg Med. 1988;5:97–100.
• 134 Daecke W, Lorenz S, Wieloch P, et al. Lunate resection and vascularized os pisiform transfer in Kienböck’s disease: an average of 10 years of follow-up study after Saffar’s procedure. J Hand Surg Am. 2005;30:677–684.
• 135 Dao KD, Solomon DJ, Shin AY, et al. The efficacy of ultrasound in the evaluation of dynamic scapholunate ligamentous instability. J Bone Joint Surg Am. 2004;86-A:1473–1478.
• 136 Davis KW, Blankenbaker DG. Imaging the ligaments and tendons of the wrist. Semin Roentgenol. 2010;45:194–217.
• 137 Davis EN, Chung KC, Kotsis SV, et al. A cost/utility analysis of open reduction and internal fixation versus cast immobilization for acute nondisplaced mid-waist scaphoid fractures. Plast Reconstr Surg. 2006;117:1223–1235.
• 138 De Beer JD, Hudson DA. Fractures of the triquetrum. J Hand Surg Br. 1987;12:52–53.
• 139 De Schrijver F, De Smet L. Isolated fracture of the capitate: the value of MRI in diagnosis and follow up. Acta Orthop Belg. 2002;68:310–315.
• 140 de Zwart AD, Beeres FJ, Kingma LM, et al. Interobserver variability among radiologists for diagnosis of scaphoid fractures by computed tomography. J Hand Surg Am. 2012;37:2252–2256.
• 141 de Zwart AD, Beeres FJ, Ring D, et al. MRI as a reference standard for suspected scaphoid fractures. Br J Radiol. 2012;85:1098–1101.
• 142 Deletang F, Segret J, Dap F, et al. Chronic scapholunate instability treated by scaphocapitate fusion: a midterm outcome perspective. Orthop Traumatol Surg Res. 2011;97(2):164–171.
• 143 Demartin F, Quinto O. Isolated dislocation of the pisiform. A case report. Chir Organi Mov. 1993;78:121–123.
• 144 Deshmukh SC, Givissis P, Belloso D, et al. Blatt’s capsulodesis for chronic scapholunate dissociation. J Hand Surg Br. 1999;24:215–220.
• 145 Dias JJ. Definition of union after acute fracture and surgery for fracture nonunion of the scaphoid. J Hand Surg Br. 2001;26:321–325.
• 146 Dias J, Brealey S, Choudhary S, et al. Scaphoid Waist Internal Fixation for Fractures Trial (SWIFFT) protocol: a pragmatic multi-centre randomised controlled trial of cast treatment versus surgical fixation for the treatment of bi-cortical, minimally displaced fractures of the scaphoid waist in adults. BMC Musculoskelet Disord. 2016;17:248.
• 147 Dias JJ, Brenkel IJ, Finlay DB. Patterns of union in fractures of the waist of the scaphoid. J Bone Joint Surg Br. 1989;71:307–310.
• 148 Dias JJ, Dhukaram V, Abhinav A, et al. Clinical and radiological outcome of cast immobilization versus surgical treatment of acute scaphoid fractures at a mean follow-up of 93 months. J Bone Joint Surg Br. 2008;90:899–905.
• 149 Dias JJ, Finlay DB, Brenkel IJ, et al. Radiographic assessment of soft tissue signs in clinically suspected scaphoid fractures: the incidence of false negative and false positive results. J Orthop Trauma. 1987;1:205–208.
• 150 Dias JJ, Hui AC, Lamont AC. Real time ultrasonography in the assessment of movement at the site of a scaphoid fracture non-union. J Hand Surg Br. 1994;19:498–504.
• 151 Dias JJ, Singh HP. Displaced fracture of the waist of the scaphoid. J Bone Joint Surg Br. 2011;93:1433–1439.
• 152 Dias JJ, Taylor M, Thompson J, et al. Radiographic signs of union of scaphoid fractures. An analysis of inter-observer agreement and reproducibility. J Bone Joint Surg Br. 1988;70:299–301.
• 153 Dias JJ, Wildin CJ, Bhowal B, et al. Should acute scaphoid fractures be fixed? A randomized controlled trial. J Bone Joint Surg Am. 2005;87:2160–2168.
• 154 DiGiovanni B, Shaffer J. Treatment of perilunate and transscaphoid perilunate dislocations of the wrist. Am J Orthop (Belle Mead NJ). 1995;24:818–826.
• 155 Dinah AF, Vickers RH. Smoking increases failure rate of operation for established non-union of the scaphoid bone. Int Orthop. 2007;31:503–505.
• 156 Ditsios K, Konstantinidis I, Agas K, et al. Comparative meta-analysis on the various vascularized bone flaps used for the treatment of scaphoid nonunion. J Orthop Res. 2017;35:1076–1085.
• 157 Dodds SD, Halim A. Scaphoid plate fixation and volar carpal artery vascularized bone graft for recalcitrant scaphoid nonunions. J Hand Surg Am. 2016;41:e191–e198.
• 158 Dodds SD, Patterson JT, Halim A. Volar plate fixation of recalcitrant scaphoid nonunions with volar carpal artery vascularized bone graft. Tech Hand Up Extrem Surg. 2014;18:2–7.
• 159 Dodds SD, Williams JB, Seiter M, et al. Lessons learned from volar plate fixation of scaphoid fracture nonunions. J Hand Surg Eur Vol. 2018;43:57–65.
• 160 Doornberg JN, Buijze GA, Ham SJ, et al. Nonoperative treatment for acute scaphoid fractures: a systematic review and meta-analysis of randomized controlled trials. J Trauma. 2011;71:1073–1081.
• 161 Dorsay TA, Major NM, Helms CA. Cost-effectiveness of immediate MR imaging versus traditional follow-up for revealing radiographically occult scaphoid fractures. AJR Am J Roentgenol. 2001;177:1257–1263.
• 162 Drac P, Manak P, Cizmar I, et al. A Palmar percutaneous volar versus a dorsal limited approach for the treatment of non- and minimally-displaced scaphoid waist fractures: an assessment of functional outcomes and complications. Acta Chir Orthop Traumatol Cech. 2010;77:143–148.
• 163 Drewniany JJ, Palmer AK, Flatt AE. The scaphotrapezial ligament complex: an anatomic and biomechanical study. J Hand Surg Am. 1985;10:492–498.
• 164 Duckworth AD, Buijze GA, Moran M, et al. Predictors of fracture following suspected injury to the scaphoid. J Bone Joint Surg Br. 2012;94:961–968.
• 165 Duckworth AD, Jenkins PJ, Aitken SA, et al. Scaphoid fracture epidemiology. J Trauma Acute Care Surg. 2012;72:E41–E45.
• 166 Duckworth AD, Ring D, McQueen MM. Assessment of the suspected fracture of the scaphoid. J Bone Joint Surg Br. 2011;93:713–719.
• 167 Dumontier C, Meyer zu Reckendorf G, Sautet A, et al. Radiocarpal dislocations: classification and proposal for treatment. A review of twenty-seven cases. J Bone Joint Surg Am. 2001;83-A:212–218.
• 168 Dunn MJ, Johnson C. Static scapholunate dissociation: a new reconstruction technique using a volar and dorsal approach in a cadaver model. J Hand Surg Am. 2001;26:749–754.
• 169 Easterling KJ, Wolfe SW. Scaphoid shift in the uninjured wrist. J Hand Surg Am. 1994;19:604–606.
• 170 Eastley N, Singh H, Dias JJ, et al. Union rates after proximal scaphoid fractures: meta-analyses and review of available evidence. J Hand Surg Eur Vol. 2013;38(8):888–897.
• 171 Eckenrode JF, Louis DS, Greene TL. Scaphoid-trapezium-trapezoid fusion in the treatment of chronic scapholunate instability. J Hand Surg Am. 1986;11:497–502.
• 172 Eddeland A, Eiken O, Hellgren E, et al. Fractures of the scaphoid. Scand J Plast Reconstr Surg. 1975;9:234–239.
• 173 Eggli S, Fernandez DL, Beck T. Unstable scaphoid fracture nonunion: a medium-term study of anterior wedge grafting procedures. J Hand Surg Br. 2002;27:36–41.
• 174 Egloff DV, Varadi G, Narakas A, et al. Silastic implants of the scaphoid and lunate. A long-term clinical study with a mean follow-up of 13 years. J Hand Surg Br. 1993;18:687–692.
• 175 El-Karef EA. Corrective osteotomy for symptomatic scaphoid malunion. Injury. 2005;36:1440–1448.
• 176 Elsaidi GA, Ruch DS, Kuzma GR, et al. Dorsal wrist ligament insertions stabilize the scapholunate interval: cadaver study. Clin Orthop Relat Res. 2004;(425):152–157.
• 177 Emmett JE, Breck LW. A review and analysis of 11,000 fractures seen in a private practice of orthopaedic surgery, 1937–1956. J Bone Joint Surg Am. 1958;40-A:1169–1175.
• 178 Englseder WA. Scapholunate dissociation occurring with scaphoid fracture. J Hand Surg Br. 1993;18:272.
• 179 Erhart J, Unger E, Schefzig P, et al. In vitro experimental investigation of the forces and torque acting on the scaphoid during light grasp. J Orthop Res. 2016;34:1734–1742.
• 180 Esberger DA. What value the scaphoid compression test?. J Hand Surg Br. 1994;19:748–749.
• 181 Evans MW Jr. Hamate hook fracture in a 17-year-old golfer: importance of matching symptoms to clinical evidence. J Manipulative Physiol Ther. 2004;27:516–518.
• 182 Evans G, Burke FD, Barton NJ. A comparison of conservative treatment and silicone replacement arthroplasty in Kienböck’s disease. J Hand Surg Br. 1986;11:98–102.
• 183 Failla JM. Hook of hamate vascularity: vulnerability to osteonecrosis and nonunion. J Hand Surg Am. 1993;18:1075–1079.
• 184 Feinstein WK, Lichtman DM, Noble PC, et al. Quantitative assessment of the midcarpal shift test. J Hand Surg Am. 1999;24:977–983.
• 185 Fenton RL. The naviculo-capitate fracture syndrome. J Bone Joint Surg Am. 1956;38-A:681–684.
• 186 Ferguson DO, Shanbhag V, Hedley H, et al. Scaphoid fracture non-union: a systematic review of surgical treatment using bone graft. J Hand Surg Eur Vol. 2016;41:492–500.
• 187 Fernandez DL, Eggli S. Scaphoid nonunion and malunion. How to correct deformity. Hand Clin. 2001;17:631–646.
• 188 Finlay K, Lee R, Friedman L. Ultrasound of intrinsic wrist ligament and triangular fibrocartilage injuries. Skeletal Radiol. 2004;33:85–90.
• 189 Fisk GR. Carpal instability and the fractured scaphoid. Ann R Coll Surg Engl. 1970;46:63–76.
• 190 Forli A, Courvoisier A, Wimsey S, et al. Perilunate dislocations and transscaphoid perilunate fracture-dislocations: a retrospective study with minimum ten-year follow-up. J Hand Surg Am. 2010;35:62–68.
• 191 Fortin PT, Louis DS. Long-term follow-up of scaphoid-trapezium-trapezoid arthrodesis. J Hand Surg Am. 1993;18:675–681.
• 192 Forward DP, Lindau TR, Melsom DS. Intercarpal ligament injuries associated with fractures of the distal part of the radius. J Bone Joint Surg Am. 2007;89:2334–2340.
• 193 Forward DP, Singh HP, Dawson S, et al. The clinical outcome of scaphoid fracture malunion at 1 year. J Hand Surg Eur Vol. 2009;34:40–46.
• 194 Foucher G, Schuind F, Merle M, et al. Fractures of the hook of the hamate. J Hand Surg Br. 1985;10:205–210.
• 195 Fowler C, Sullivan B, Williams LA, et al. A comparison of bone scintigraphy and MRI in the early diagnosis of the occult scaphoid waist fracture. Skeletal Radiol. 1998;27:683–687.
• 196 Frankel VH. The Terry-Thomas sign. Clin Orthop Relat Res. 1977;(129):321–322.
• 197 Freedman DM, Botte MJ, Gelberman RH. Vascularity of the carpus. Clin Orthop Relat Res. 2001;(383):47–59.
• 198 Freeland P. Scaphoid tubercle tenderness: a better indicator of scaphoid fractures?. Arch Emerg Med. 1989;6:46–50.
• 199 Freeland AE, Finley JS. Displaced vertical fracture of the trapezium treated with a small cancellous lag screw. J Hand Surg Am. 1984;9:843–845.
• 200 Freeland AE, Pesut TA. Oblique capitate fracture of the wrist. Orthopedics. 2004;27:287–290.
• 201 Fusetti C, Poletti PA, Pradel PH, et al. Diagnosis of occult scaphoid fracture with high-spatial-resolution sonography: a prospective blind study. J Trauma. 2005;59:677–681.
• 202 Futami T, Aoki H, Tsukamoto Y. Fractures of the hook of the hamate in athletes. 8 cases followed for 6 years. Acta Orthop Scand. 1993;64:469–471.
• 203 Gaebler C, Kukla C, Breitenseher M, et al. Magnetic resonance imaging of occult scaphoid fractures. J Trauma. 1996;41:73–76.
• 204 Gaebler C, Kukla C, Breitenseher MJ, et al. Limited diagnostic value of macroradiography in suspected scaphoid fractures. Acta Orthop Scand. 1998;69:401–403.
• 205 Gabler C, Kukla C, Breitenseher MJ, et al. Diagnosis of occult scaphoid fractures and other wrist injuries. Are repeated clinical examinations and plain radiographs still state of the art?. Langenbecks Arch Surg. 2001;386:150–154.
• 206 Gaebler C, McQueen MM. Carpus fractures and dislocations. In: Bucholz RW, Heckman JD, Court-Brown CM, et al., eds. Rockwood and Green’s Fractures in Adults. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:781–828.
• 207 Gajendran VK, Peterson B, Slater RR Jr, et al. Long-term outcomes of dorsal intercarpal ligament capsulodesis for chronic scapholunate dissociation. J Hand Surg Am. 2007;32:1323–1333.
• 208 Ganel A, Engel J, Oster Z, et al. Bone scanning in the assessment of fractures of the scaphoid. J Hand Surg Am. 1979;4:540–543.
• 209 Garala K, Taub NA, Dias JJ. The epidemiology of fractures of the scaphoid: impact of age, gender, deprivation and seasonality. Bone Joint J. 2016;98-B:654–659.
• 210 Garcia-Elias M. Dorsal fractures of the triquetrum-avulsion or compression fractures?. J Hand Surg Am. 1987;12:266–268.
• 211 Garcia-Elias M. The non-dissociative clunking wrist: a personal view. J Hand Surg Eur Vol. 2008;33:698–711.
• 212 Garcia-Elias M, Bishop AT, Dobyns JH, et al. Transcarpal carpometacarpal dislocations, excluding the thumb. J Hand Surg Am. 1990;15:531–540.
• 213 Garcia-Elias M, Henriquez-Lluch A, Rossignani P, et al. Bennett’s fracture combined with fracture of the trapezium. A report of three cases. J Hand Surg Br. 1993;18:523–526.
• 214 Garcia-Elias M, Lluch A. Partial excision of scaphoid: is it ever indicated?. Hand Clin. 2001;17:687–695.
• 215 Garcia-Elias M, Lluch AL, Stanley JK. Three-ligament tenodesis for the treatment of scapholunate dissociation: indications and surgical technique. J Hand Surg Am. 2006;31:125–134.
• 216 Gardner MJ, Crisco JJ, Wolfe SW. Carpal kinematics. Hand Clin. 2006;22:413–420.
• 217 Geijer M, Borjesson AM, Gothlin JH. Clinical utility of tomosynthesis in suspected scaphoid fracture. A pilot study. Skeletal Radiol. 2011;40:863–867.
• 218 Geissler WB, Freeland AE, Savoie FH, et al. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg Am. 1996;78:357–365.
• 219 Geissler WB, Hammit MD. Arthroscopic aided fixation of scaphoid fractures. Hand Clin. 2001;17:575–588, viii.
• 220 Gelberman RH, Bauman TD, Menon J, et al. The vascularity of the lunate bone and Kienböck’s disease. J Hand Surg Am. 1980;5:272–278.
• 221 Gelberman RH, Cooney WP 3rd, Szabo RM. Carpal instability. Instr Course Lect. 2001;50:123–134.
• 222 Gelberman RH, Gross MS. The vascularity of the wrist. Identification of arterial patterns at risk. Clin Orthop Relat Res. 1986;40–49.
• 223 Gelberman RH, Menon J. The vascularity of the scaphoid bone. J Hand Surg Am. 1980;5:508–513.
• 224 Gelberman RH, Panagis JS, Taleisnik J, et al. The arterial anatomy of the human carpus. Part I: The extraosseous vascularity. J Hand Surg Am. 1983;8:367–375.
• 225 Gelberman RH, Wolock BS, Siegel DB. Fractures and non-unions of the carpal scaphoid. J Bone Joint Surg Am. 1989;71:1560–1565.
• 226 Gellman H, Caputo RJ, Carter V, et al. Comparison of short and long thumb-spica casts for non-displaced fractures of the carpal scaphoid. J Bone Joint Surg Am. 1989;71:354–357.
• 227 Gellman H, Schwartz SD, Botte MJ, et al. Late treatment of a dorsal transscaphoid, transtriquetral perilunate wrist dislocation with avascular changes of the lunate. Clin Orthop Relat Res. 1988;196–203.
• 228 Geoghegan JM, Woodruff MJ, Bhatia R, et al. Undisplaced scaphoid waist fractures: is 4 weeks’ immobilization in a below-elbow cast sufficient if a week 4 CT scan suggests fracture union?. J Hand Surg Eur Vol. 2009;34:631–637.
• 229 Geurts G, van Riet R, Meermans G, et al. Incidence of scaphotrapezial arthritis following volar percutaneous fixation of nondisplaced scaphoid waist fractures using a transtrapezial approach. J Hand Surg Am. 2011;36:1753–1758.
• 230 Geurts GF, van Riet RP, Meermans G, et al. Volar percutaneous transtrapezial fixation of scaphoid waist fractures: surgical technique. Acta Orthop Belg. 2012;78:121–125.
• 231 Gillette BP, Amadio PC, Kakar S. Long-term outcomes of scaphoid malunion. Hand (NY). 2017;12:26–30.
• 232 Gilula LA, Destouet JM, Weeks PM, et al. Roentgenographic diagnosis of the painful wrist. Clin Orthop Relat Res. 1984;52–64.
• 233 Gilula LA, Weeks PM. Post-traumatic ligamentous instabilities of the wrist. Radiology. 1978;129:641–651.
• 234 Gooding A, Coates M, Rothwell A. Cost analysis of traditional follow-up protocol versus MRI for radiographically occult scaphoid fractures: a pilot study for the Accident Compensation Corporation. N Z Med J. 2004;117:U1049.
• 235 Gradl G, Neuhaus V, Fuchsberger T, et al. Radiographic diagnosis of scapholunate dissociation among intra-articular fractures of the distal radius: interobserver reliability. J Hand Surg Am. 2013;38:1685–1690.
• 236 Graner O, Lopes EI, Carvalho BC, et al. Arthrodesis of the carpal bones in the treatment of Kienböck’s disease, painful ununited fractures of the navicular and lunate bones with avascular necrosis, and old fracture-dislocations of carpal bones. J Bone Joint Surg Am. 1966;48:767–774.
• 237 Green DP. The effect of avascular necrosis on Russe bone grafting for scaphoid nonunion. J Hand Surg Am. 1985;10:597–605.
• 238 Green DP, O’Brien ET. Classification and management of carpal dislocations. Clin Orthop Relat Res. 1980;55–72.
• 239 Gregory JJ, Mohil RS, Ng AB, et al. Comparison of Herbert and Acutrak screws in the treatment of scaphoid non-union and delayed union. Acta Orthop Belg. 2008;74:761–765.
• 240 Grewal R, Lutz K, MacDermid JC, et al. Proximal pole scaphoid fractures: a computed tomographic assessment of outcomes. J Hand Surg Am. 2016;41:54–58.
• 241 Grewal R, Suh N, MacDermid JC. Use of computed tomography to predict union and time to union in acute scaphoid fractures treated nonoperatively. J Hand Surg Am. 2013;38:872–877.
• 242 Grewal R, Suh N, MacDermid JC. The missed scaphoid fracture-outcomes of delayed cast treatment. J Wrist Surg. 2015;4:278–283.
• 243 Grewal R, Suh N, MacDermid JC. Is Casting for non-displaced simple scaphoid waist fracture effective? A CT based assessment of union. Open Orthop J. 2016;10:431–438.
• 244 Griffin AC, Gilula LA, Young VL, et al. Fracture of the dorsoulnar tubercle of the trapezium. J Hand Surg Am. 1988;13:622–626.
• 245 Grover R. Clinical assessment of scaphoid injuries and the detection of fractures. J Hand Surg Br. 1996;21:341–343.
• 246 Groves AM, Kayani I, Syed R, et al. An international survey of hospital practice in the imaging of acute scaphoid trauma. AJR Am J Roentgenol. 2006;187:1453–1456.
• 247 Gruson KI, Kaplan KM, Paksima N. Isolated trapezoid fractures: a case report with compilation of the literature. Bull NYU Hosp Jt Dis. 2008;66:57–60.
• 248 Gupta R, Bingenheimer E, Fornalski S, et al. The effect of ulnar shortening on lunate and triquetrum motion—a cadaveric study. Clin Biomech (Bristol, Avon). 2005;20:839–845.
• 249 Gupta A, Risitano G, Crawford R, et al. Fractures of the hook of the hamate. Injury. 1989;20:284–286.
• 250 Gutow AP. Percutaneous fixation of scaphoid fractures. J Am Acad Orthop Surg. 2007;15:474–485.
• 251 Ha NB, Phadnis J, MacLean SBM, et al. Radioscapholunate fusion with triquetrum and distal pole of scaphoid excision: long-term follow-up. J Hand Surg Eur Vol. 2018;43:168–173.
• 252 Haddad FS, Goddard NJ. Acute percutaneous scaphoid fixation. A pilot study. J Bone Joint Surg Br. 1998;80:95–99.
• 253 Haddad FS, Goddard NJ. Acutrak percutaneous scaphoid fixation. Tech Hand Up Extrem Surg. 2000;4:78–80.
• 254 Hambidge JE, Desai VV, Schranz PJ, et al. Acute fractures of the scaphoid. Treatment by cast immobilization with the wrist in flexion or extension?. J Bone Joint Surg Br. 1999;81:91–92.
• 255 Hansen TB, Petersen RB, Barckman J, et al. Cost-effectiveness of MRI in managing suspected scaphoid fractures. J Hand Surg Eur Vol. 2009;34(5):627–630.
• 256 Haussman P. Long-term results after silicone prosthesis replacement of the proximal pole of the scaphoid bone in advanced scaphoid nonunion. J Hand Surg Br. 2002;27:417–423.
• 257 Herbert TJ. The Fractured Scaphoid. St Louis, MO: Quality Medical Publishing; 1990.
• 258 Herbert TJ. Open volar repair of acute scaphoid fractures. Hand Clin. 2001;17:589–599, viii.
• 259 Herbert TJ, Fisher WE. Management of the fractured scaphoid using a new bone screw. J Bone Joint Surg Br. 1984;66:114–123.
• 260 Herneth AM, Siegmeth A, Bader TR, et al. Scaphoid fractures: evaluation with high-spatial-resolution US initial results. Radiology. 2001;220:231–235.
• 261 Herzberg G. Perilunate and axial carpal dislocations and fracture-dislocations. J Hand Surg Am. 2008;33:1659–1668.
• 262 Herzberg G, Comtet JJ, Linscheid RL, et al. Perilunate dislocations and fracture-dislocations: a multicenter study. J Hand Surg Am. 1993;18:768–779.
• 263 Herzberg G, Forissier D. Acute dorsal trans-scaphoid perilunate fracture-dislocations: medium-term results. J Hand Surg Br. 2002;27:498–502.
• 264 Hey HW, Chong AK, Murphy D. Prevalence of carpal fracture in Singapore. J Hand Surg Am. 2011;36:278–283.
• 265 Hildebrand KA, Ross DC, Patterson SD, et al. Dorsal perilunate dislocations and fracture-dislocations: questionnaire, clinical, and radiographic evaluation. J Hand Surg Am. 2000;25:1069–1079.
• 266 Hirano K, Inoue G. Classification and treatment of hamate fractures. Hand Surg. 2005;10:151–157.
• 267 Hocker K, Menschik A. Chip fractures of the triquetrum. Mechanism, classification and results. J Hand Surg Br. 1994;19:584–588.
• 268 Hodgkinson JP, Parkinson RW, Davies DR. Simultaneous fracture of the carpal scaphoid and trapezium—a very unusual combination of fractures. J Hand Surg Br. 1985;10:393–394.
• 269 Hofmeister EP, Dao KD, Glowacki KA, et al. The role of midcarpal arthroscopy in the diagnosis of disorders of the wrist. J Hand Surg Am. 2001;26:407–414.
• 270 Horii E, Nakamura R, Watanabe K, et al. Scaphoid fracture as a “puncher’s fracture.” J Orthop Trauma. 1994;8:107–110.
• 271 Houshian S, Schroder HA. Wrist arthrodesis with the AO titanium wrist fusion plate: a consecutive series of 42 cases. J Hand Surg Br. 2001;26:355–359.
• 272 Hove LM. Fractures of the hand. Distribution and relative incidence. Scand J Plast Reconstr Surg Hand Surg. 1993;27:317–319.
• 273 Hove LM. Simultaneous scaphoid and distal radial fractures. J Hand Surg Br. 1994;19:384–388.
• 274 Hove LM. Epidemiology of scaphoid fractures in Bergen, Norway. Scand J Plast Reconstr Surg Hand Surg. 1999;33:423–426.
• 275 Hsu AR, Hsu PA. Unusual case of isolated lunate fracture without ligamentous injury. Orthopedics. 2011;34:e785–e789.
• 276 Hsu KY, Wu CC, Wang KC, et al. Simultaneous dislocation of the five carpometacarpal joints with concomitant fractures of the tuberosity of the trapezium and the hook of the hamate: case report. J Trauma. 1993;35:479–483.
• 277 Iacobellis C, Baldan S, Aldegheri R. Percutaneous screw fixation for scaphoid fractures. Musculoskelet Surg. 2011;95:199–203.
• 278 Ibrahim T, Qureshi A, Sutton AJ, et al. Surgical versus nonsurgical treatment of acute minimally displaced and undisplaced scaphoid waist fractures: pairwise and network meta-analyses of randomized controlled trials. J Hand Surg Am. 2011;36:1759–1768.
• 279 Ilyas AM, Mudgal CS. Radiocarpal fracture-dislocations. J Am Acad Orthop Surg. 2008;16:647–655.
• 280 Imaeda T, Nakamura R, Miura T, et al. Magnetic resonance imaging in scaphoid fractures. J Hand Surg Br. 1992;17:20–27.
• 281 Inoue G, Miura T. Proximal row carpectomy in perilunate dislocations and lunatomalacia. Acta Orthop Scand. 1990;61:449–452.
• 282 Jenkins PJ, Slade K, Huntley JS, et al. A comparative analysis of the accuracy, diagnostic uncertainty and cost of imaging modalities in suspected scaphoid fractures. Injury. 2008;39:768–774.
• 283 Jensen BV, Christensen C. An unusual combination of simultaneous fracture of the tuberosity of the trapezium and the hook of the hamate. J Hand Surg Am. 1990;15:285–287.
• 284 Jeon IH, Kim HJ, Min WK, et al. Arthroscopically assisted percutaneous fixation for trans-scaphoid perilunate fracture dislocation. J Hand Surg Eur Vol. 2010;35:664–668.
• 285 Jeon IH, Micic ID, Oh CW, et al. Percutaneous screw fixation for scaphoid fracture: a comparison between the dorsal and the volar approaches. J Hand Surg Am. 2009;34:228–236.
• 286 Johnson RP. The acutely injured wrist and its residuals. Clin Orthop Relat Res. 1980;(149):33–44.
• 287 Jones WA. Beware the sprained wrist. The incidence and diagnosis of scapholunate instability. J Bone Joint Surg Br. 1988;70:293–297.
• 288 Jones DB Jr, Burger H, Bishop AT, et al. Treatment of scaphoid waist nonunions with an avascular proximal pole and carpal collapse. A comparison of two vascularized bone grafts. J Bone Joint Surg Am. 2008;90:2616–2625.
• 289 Jones DB Jr, Kakar S. Perilunate dislocations and fracture dislocations. J Hand Surg Am. 2012;37:2168–2173.
• 290 Jonsson BY, Siggeirsdottir K, Mogensen B, et al. Fracture rate in a population-based sample of men in Reykjavik. Acta Orthop Scand. 2004;75:195–200.
• 291 Jorgsholm P, Thomsen NO, Bjorkman A, et al. The incidence of intrinsic and extrinsic ligament injuries in scaphoid waist fractures. J Hand Surg Am. 2010;35:368–374.
• 292 Kadar A, Bishop AT, Suchyta MA, et al. Diagnosis and management of hook of hamate fractures. J Hand Surg Eur Vol. 2018;43:539–545.
• 293 Kailu L, Zhou X, Fuguo H. Chronic perilunate dislocations treated with open reduction and internal fixation: results of medium-term follow-up. Int Orthop. 2010;34:1315–1320.
• 294 Kain N, Heras-Palou C. Trapezoid fractures: report of 11 cases. J Hand Surg Am. 2012;37:1159–1162.
• 295 Kang KB, Kim HJ, Park JH, et al. Comparison of dorsal and volar percutaneous approaches in acute scaphoid fractures: a meta-analysis. PLoS One. 2016;11:e0162779.
• 296 Karl JW, Swart E, Strauch RJ. Diagnosis of occult scaphoid fractures: a cost-effectiveness analysis. J Bone Joint Surg Am. 2015;97:1860–1868.
• 297 Kato H, Nakamura R, Horii E, et al. Diagnostic imaging for fracture of the hook of the hamate. Hand Surg. 2000;5:19–24.
• 298 Kauer JM. Functional anatomy of the wrist. Clin Orthop Relat Res. 1980;(149):9–20.
• 299 Kauer JM. The mechanism of the carpal joint. Clin Orthop Relat Res. 1986;(202):16–26.
• 300 Kaufmann R, Pfaeffle J, Blankenhorn B, et al. Kinematics of the midcarpal and radiocarpal joints in radioulnar deviation: an in vitro study. J Hand Surg Am. 2005;30:937–942.
• 301 Kaufmann RA, Pfaeffle HJ, Blankenhorn BD, et al. Kinematics of the midcarpal and radiocarpal joint in flexion and extension: an in vitro study. J Hand Surg Am. 2006;31:1142–1148.
• 302 Kawamura K, Chung KC. Treatment of scaphoid fractures and nonunions. J Hand Surg Am. 2008;33:988–997.
• 303 Kijima Y, Viegas SF. Wrist anatomy and biomechanics. J Hand Surg Am. 2009;34:1555–1563.
• 304 Kim J, Park JW, Chung J, et al. Non-vascularized iliac bone grafting for scaphoid nonunion with avascular necrosis. J Hand Surg Eur Vol. 2018;43:24–31.
• 305 Kitay A, Wolfe SW. Scapholunate instability: current concepts in diagnosis and management. J Hand Surg Am. 2012;37:2175–2196.
• 306 Knoll VD, Allan C, Trumble TE. Trans-scaphoid perilunate fracture dislocations: results of screw fixation of the scaphoid and lunotriquetral repair with a dorsal approach. J Hand Surg Am. 2005;30:1145–1152.
• 307 Komurcu M, Kurklu M, Ozturan KE, et al. Early and delayed treatment of dorsal transscaphoid perilunate fracture-dislocations. J Orthop Trauma. 2008;22:535–540.
• 308 Kozin SH. Perilunate injuries: diagnosis and treatment. J Am Acad Orthop Surg. 1998;6:114–120.
• 309 Kozin SH. The role of arthroscopy in scapholunate instability. Hand Clin. 1999;15:435–444.
• 310 Kozin SH. Incidence, mechanism, and natural history of scaphoid fractures. Hand Clin. 2001;17:515–524.
• 311 Kremer T, Wendt M, Riedel K, et al. Open reduction for perilunate injuries—clinical outcome and patient satisfaction. J Hand Surg Am. 2010;35:1599–1606.
• 312 Kuhlmann JN, Boabighi A, Kirsch JM, et al. Experimental study on a plaster cast in fractures of the carpal scaphoid. Clinical deductions. Rev Chir Orthop Reparatrice Appar Mot. 1987;73:49–56.
• 313 Kuo CE, Wolfe SW. Scapholunate instability: current concepts in diagnosis and management. J Hand Surg Am. 2008;33:998–1013.
• 314 Kusano N, Churei Y, Shiraishi E, et al. Diagnosis of occult carpal scaphoid fracture: a comparison of magnetic resonance imaging and computed tomography techniques. Tech Hand Up Extrem Surg. 2002;6:119–123.
• 315 Kwon BC, Baek GH. Fluoroscopic diagnosis of scapholunate interosseous ligament injuries in distal radius fractures. Clin Orthop Relat Res. 2008;466:969–976.
• 316 Lacelli F, Muda A, Sconfienza LM, et al. High-resolution ultrasound anatomy of extrinsic carpal ligaments. Radiol Med. 2008;113:504–516.
• 317 Lacey JD, Hodge JC. Pisiform and hamulus fractures: easily missed wrist fractures diagnosed on a reverse oblique radiograph. J Emerg Med. 1998;16:445–452.
• 318 LaJoie AS, McCabe SJ, Thomas B, et al. Determining the sensitivity and specificity of common diagnostic tests for carpal tunnel syndrome using latent class analysis. Plast Reconstr Surg. 2005;116:502–507.
• 319 Lam KS, Woodbridge S, Burke FD. Wrist function after excision of the pisiform. J Hand Surg Br. 2003;28:69–72.
• 320 Lamas C, Carrera A, Proubasta I, et al. The anatomy and vascularity of the lunate: considerations applied to Kienböck’s disease. Chir Main. 2007;26:13–20.
• 321 Landsmeer JM. Studies in the anatomy of articulation. I. The equilibrium of the “intercalated” bone. Acta Morphol Neerl Scand. 1961;3:287–303.
• 322 Lane LB, Daher RJ, Leo AJ. Scapholunate dissociation with radiolunate arthritis without radioscaphoid arthritis. J Hand Surg Am. 2010;35:1075–1081.
• 323 Langer Andersen J, Gron P, Langhoff O. The scaphoid fat stripe in the diagnosis of carpal trauma. Acta Radiol. 1988;29:97–99.
• 324 Langhoff O, Andersen JL. Consequences of late immobilization of scaphoid fractures. J Hand Surg Br. 1988;13:77–79.
• 325 Larsen CF, Brondum V, Skov O. Epidemiology of scaphoid fractures in Odense, Denmark. Acta Orthop Scand. 1992;63:216–218.
• 326 Lavernia CJ, Cohen MS, Taleisnik J. Treatment of scapholunate dissociation by ligamentous repair and capsulodesis. J Hand Surg Am. 1992;17:354–359.
• 327 Lee SB, Kim HJ, Chun JM, et al. Osseous microarchitecture of the scaphoid: cadaveric study of regional variations and clinical implications. Clin Anat. 2012;25:203–211.
• 328 Lee SK, Zlotolow DA, Sapienza A, et al. Biomechanical comparison of 3 methods of scapholunate ligament reconstruction. J Hand Surg Am. 2014;39:643–650.
• 329 Leslie IJ, Dickson RA. The fractured carpal scaphoid. Natural history and factors influencing outcome. J Bone Joint Surg Br. 1981;63-B:225–230.
• 330 Leung YF, Ip SP, Wong A, et al. Transscaphoid transcapitate transtriquetral perilunate fracture-dislocation: a case report. J Hand Surg Am. 2006;31:608–610.
• 331 Levy M, Fischel RE, Stern GM, et al. Chip fractures of the os triquetrum: the mechanism of injury. J Bone Joint Surg Br. 1979;61-B:355–357.
• 332 Li G, Rowen B, Tokunaga D, et al. Carpal kinematics of lunotriquetral dissociations. Biomed Sci Instrum. 1991;27:273–281.
• 333 Lichtman DM, Bruckner JD, Culp RW, et al. Palmar midcarpal instability: results of surgical reconstruction. J Hand Surg Am. 1993;18:307–315.
• 334 Lichtman DM, Schneider JR, Swafford AR, et al. Ulnar midcarpal instability-clinical and laboratory analysis. J Hand Surg Am. 1981;6:515–523.
• 335 Linscheid RL. Kinematic considerations of the wrist. Clin Orthop Relat Res. 1986;(202):27–39.
• 336 Linscheid RL. Biomechanics of the distal radioulnar joint. Clin Orthop Relat Res. 1992;(275):46–55.
• 337 Linscheid RL, Dobyns JH. The unified concept of carpal injuries. Ann Chir Main. 1984;3:35–42.
• 338 Linscheid RL, Dobyns JH. Treatment of scapholunate dissociation. Rotatory subluxation of the scaphoid. Hand Clin. 1992;8:645–652.
• 339 Linscheid RL, Dobyns JH, Beabout JW, et al. Traumatic instability of the wrist: diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54:1612–1632.
• 340 Linscheid RL, Dobyns JH, Beckenbaugh RD, et al. Instability patterns of the wrist. J Hand Surg Am. 1983;8:682–686.
• 341 Linscheid RL, Lynch NM. Scaphoid osteotomy for malunion. Tech Hand Up Extrem Surg. 1998;2:119–125.
• 342 Little CP, Burston BJ, Hopkinson-Woolley J, et al. Failure of surgery for scaphoid non-union is associated with smoking. J Hand Surg Br. 2006;31:252–255.
• 343 Liu B, Chen SL, Zhu J, et al. Arthroscopically assisted mini-invasive management of perilunate dislocations. J Wrist Surg. 2015;4:93–100.
• 344 Llewelyn H. Assessing properly the usefulness of clinical prediction rules and tests. BMJ. 2012;344:e1238.
• 345 Logan SE, Nowak MD. Intrinsic and extrinsic wrist ligaments: biomechanical and functional differences. Biomed Sci Instrum. 1987;23:9–13.
• 346 Low G, Raby N. Can follow-up radiography for acute scaphoid fracture still be considered a valid investigation?. Clin Radiol. 2005;60:1106–1110.
• 347 Lozano-Calderon S, Blazar P, Zurakowski D, et al. Diagnosis of scaphoid fracture displacement with radiography and computed tomography. J Bone Joint Surg Am. 2006;88:2695–2703.
• 348 Lutz M, Arora R, Kammerlander C, et al. Stabilization of perilunate and transscaphoid perilunate fracture-dislocations via a combined palmar and dorsal approach. Oper Orthop Traumatol. 2009;21:442–458.
• 349 Lynch NM, Linscheid RL. Corrective osteotomy for scaphoid malunion: technique and long-term follow-up evaluation. J Hand Surg Am. 1997;22:35–43.
• 350 Mack GR, Bosse MJ, Gelberman RH, et al. The natural history of scaphoid non-union. J Bone Joint Surg Am. 1984;66:504–509.
• 351 Mahmoud M, Koptan W. Percutaneous screw fixation without bone grafting for established scaphoid nonunion with substantial bone loss. J Bone Joint Surg Br. 2011;93:932–936.
• 352 Mallee W, Doornberg JN, Ring D, et al. Comparison of CT and MRI for diagnosis of suspected scaphoid fractures. J Bone Joint Surg Am. 2011;93:20–28.
• 353 Mallee WH, Henny EP, van Dijk CN, et al. Clinical diagnostic evaluation for scaphoid fractures: a systematic review and meta-analysis. J Hand Surg Am. 2014;39:1683–1691.
• 354 Mallee WH, Mellema JJ, Guitton TG, et al. 6-week radiographs unsuitable for diagnosis of suspected scaphoid fractures. Arch Orthop Trauma Surg. 2016;136:771–778.
• 355 Mallee WH, Wang J, Poolman RW, et al. Computed tomography versus magnetic resonance imaging versus bone scintigraphy for clinically suspected scaphoid fractures in patients with negative plain radiographs. Cochrane Database Syst Rev. 2015;(6):CD010023.
• 356 Malshikare V, Oswal A. Trapezoid fracture caused by assault. Indian J Orthop. 2007;41:175–176.
• 357 Mansberg R, Lewis G, Kirsh G. Avascular necrosis and fracture of the capitate bone: unusual scintigraphic features. Clin Nucl Med. 2000;25:372–373.
• 358 Marcuzzi A, Leti AA, Caserta G, et al. Ligamentous reconstruction of scapholunate dislocation through a double dorsal and palmar approach. J Hand Surg Br. 2006;31:445–449.
• 359 Marsh AP, Lampros PJ. The naviculo-capitate fracture syndrome. Am J Roentgenol Radium Ther Nucl Med. 1959;82:255–256.
• 360 Martus JE, Bedi A, Jebson PJ. Cannulated variable pitch compression screw fixation of scaphoid fractures using a limited dorsal approach. Tech Hand Up Extrem Surg. 2005;9:202–206.
• 361 Mataliotakis G, Doukas M, Kostas I, et al. Sensory innervation of the subregions of the scapholunate interosseous ligament in relation to their structural composition. J Hand Surg Am. 2009;34:1413–1421.
• 362 May O. The pisiform bone: sesamoid or carpal bone?. Ann Chir Main Memb Super. 1996;15:265–271.
• 363 Mayfield JK. Mechanism of carpal injuries. Clin Orthop Relat Res. 1980;45–54.
• 364 Mayfield JK. Patterns of injury to carpal ligaments. A spectrum. Clin Orthop Relat Res. 1984;36–42.
• 365 Mayfield JK. Wrist ligamentous anatomy and pathogenesis of carpal instability. Orthop Clin North Am. 1984;15:209–216.
• 366 Mayfield JK, Johnson RP, Kilcoyne RF. The ligaments of the human wrist and their functional significance. Anat Rec. 1976;186:417–428.
• 367 Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg Am. 1980;5:226–241.
• 368 McLaughlin HL. Fracture of the carpal navicular (scaphoid) bone; some observations based on treatment by open reduction and internal fixation. J Bone Joint Surg Am. 1954;36-A:765–774.
• 369 McMurtry RY, Youm Y, Flatt AE, et al. Kinematics of the wrist. II. Clinical applications. J Bone Joint Surg Am. 1978;60:955–961.
• 370 McQueen MM, Gelbke MK, Wakefield A, et al. Percutaneous screw fixation versus conservative treatment for fractures of the waist of the scaphoid: a prospective randomised study. J Bone Joint Surg Br. 2008;90:66–71.
• 371 Meermans G, Verstreken F. Percutaneous transtrapezial fixation of acute scaphoid fractures. J Hand Surg Eur Vol. 2008;33:791–796.
• 372 Megerle K, Bertel D, Germann G, et al. Long-term results of dorsal intercarpal ligament capsulodesis for the treatment of chronic scapholunate instability. J Bone Joint Surg Br. 2012;94:1660–1665.
• 373 Megerle K, Pohlmann S, Kloeters O, et al. The significance of conventional radiographic parameters in the diagnosis of scapholunate ligament lesions. Eur Radiol. 2011;21:176–181.
• 374 Megerle K, Worg H, Christopoulos G, et al. Gadolinium-enhanced preoperative MRI scans as a prognostic parameter in scaphoid nonunion. J Hand Surg Eur Vol. 2011;36:23–28.
• 375 Mehrpour SR, Kamrani RS, Aghamirsalim MR, et al. Treatment of Kienböck disease by lunate core decompression. J Hand Surg Am. 2011;36:1675–1677.
• 376 Memarsadeghi M, Breitenseher MJ, Schaefer-Prokop C, et al. Occult scaphoid fractures: comparison of multidetector CT and MR imaging: initial experience. Radiology. 2006;240:169–176.
• 377 Menth-Chiari WA, Poehling GG. Preiser’s disease: arthroscopic treatment of avascular necrosis of the scaphoid. Arthroscopy. 2000;16:208–213.
• 378 Merrell GA, Wolfe SW, Slade JF 3rd. Treatment of scaphoid nonunions: quantitative meta-analysis of the literature. J Hand Surg Am. 2002;27:685–691.
• 379 Meyers MH, Wells R, Harvey JP Jr. Naviculo-capitate fracture syndrome. Review of the literature and a case report. J Bone Joint Surg Am. 1971;53:1383–1386.
• 380 Milek MA, Boulas HJ. Flexor tendon ruptures secondary to hamate hook fractures. J Hand Surg Am. 1990;15:740–744.
• 381 Minami A, Kato H, Iwasaki N. Treatment of scapholunate dissociation: ligamentous repair associated with modified dorsal capsulodesis. Hand Surg. 2003;8:1–6.
• 382 Mirrer J, Yeung J, Sapienza A. Anatomic locking plate fixation for scaphoid nonunion. Case Rep Orthop. 2016;2016:7374101.
• 383 Mitsuyasu H, Patterson RM, Shah MA, et al. The role of the dorsal intercarpal ligament in dynamic and static scapholunate instability. J Hand Surg Am. 2004;29:279–288.
• 384 Miyawaki T, Kobayashi M, Matsuura S, et al. Trapezoid bone fracture. Ann Plast Surg. 2000;44:444–446.
• 385 Mody BS, Belliappa PP, Dias JJ, et al. Nonunion of fractures of the scaphoid tuberosity. J Bone Joint Surg Br. 1993;75:423–425.
• 386 Mody BS, Dias JJ. Carpometacarpal dislocation of the thumb associated with fracture of the trapezium. J Hand Surg Br. 1993;18:197–199.
• 387 Moneim MS. Management of greater arc carpal fractures. Hand Clin. 1988;4:457–467.
• 388 Moneim MS, Bolger JT, Omer GE. Radiocarpal dislocation—classification and rationale for management. Clin Orthop Relat Res. 1985;199–209.
• 389 Moneim MS, Hofammann KE 3rd, Omer GE. Transscaphoid perilunate fracture-dislocation. Result of open reduction and pin fixation. Clin Orthop Relat Res. 1984;227–235.
• 390 Moojen TM, Snel JG, Ritt MJ, et al. In vivo analysis of carpal kinematics and comparative review of the literature. J Hand Surg Am. 2003;28:81–87.
• 391 Morgan WJ, Breen TF, Coumas JM, et al. Role of magnetic resonance imaging in assessing factors affecting healing in scaphoid nonunions. Clin Orthop Relat Res. 1997;240–246.
• 392 Moritomo H. Radiographic clues for determining carpal instability and treatment protocol for scaphoid fractures. J Orthop Sci. 2014;19:379–383.
• 393 Moritomo H, Murase T, Oka K, et al. Relationship between the fracture location and the kinematic pattern in scaphoid nonunion. J Hand Surg Am. 2008;33:1459–1468.
• 394 Moritomo H, Viegas SF, Elder KW, et al. Scaphoid nonunions: a 3-dimensional analysis of patterns of deformity. J Hand Surg Am. 2000;25:520–528.
• 395 Moritomo H, Viegas SF, Nakamura K, et al. The scaphotrapezio-trapezoidal joint. Part 1: An anatomic and radiographic study. J Hand Surg Am. 2000;25:899–910.
• 396 Morizaki Y, Miura T. Unusual pattern of dislocation of the trapeziometacarpal joint with avulsion fracture of the trapezium: case report. Hand Surg. 2009;14:149–152.
• 397 Mudgal C, Hastings H. Scapho-lunate diastasis in fractures of the distal radius. Pathomechanics and treatment options. J Hand Surg Br. 1993;18:725–729.
• 398 Mudgal CS, Jones WA. Scapho-lunate diastasis: a component of fractures of the distal radius. J Hand Surg Br. 1990;15:503–505.
• 399 Mudgal CS, Psenica J, Jupiter JB. Radiocarpal fracture-dislocation. J Hand Surg Br. 1999;24:92–98.
• 400 Muermans S, De Smet L, Van Ransbeeck H. Blatt dorsal capsulodesis for scapholunate instability. Acta Orthop Belg. 1999;65:434–439.
• 401 Mulford JS, Ceulemans LJ, Nam D, et al. Proximal row carpectomy vs four corner fusion for scapholunate (SLAC) or scaphoid nonunion advanced collapse (SNAC) wrists: a systematic review of outcomes. J Hand Surg Eur Vol. 2009;34:256–263.
• 402 Muniz AE. Unusual wrist pain: pisiform dislocation and fracture. Am J Emerg Med. 1999;17:78–79.
• 403 Munk B, Bolvig L, Kroner K, et al. Ultrasound for diagnosis of scaphoid fractures. J Hand Surg Br. 2000;25:369–371.
• 404 Munk B, Frokjaer J, Larsen CF, et al. Diagnosis of scaphoid fractures. A prospective multicenter study of 1,052 patients with 160 fractures. Acta Orthop Scand. 1995;66:359–360.
• 405 Munk B, Larsen CF. Bone grafting the scaphoid nonunion: a systematic review of 147 publications including 5,246 cases of scaphoid nonunion. Acta Orthop Scand. 2004;75:618–629.
• 406 Murphy DG, Eisenhauer MA, Powe J, et al. Can a day 4 bone scan accurately determine the presence or absence of scaphoid fracture?. Ann Emerg Med. 1995;26:434–438.
• 407 Nagao S, Patterson RM, Buford WL Jr, et al. Three-dimensional description of ligamentous attachments around the lunate. J Hand Surg Am. 2005;30:685–692.
• 408 Nagumo A, Toh S, Tsubo K, et al. An occult fracture of the trapezoid bone. A case report. J Bone Joint Surg Am. 2002;84-A:1025–1027.
• 409 Nakamura R, Imaeda T, Horii E, et al. Analysis of scaphoid fracture displacement by three-dimensional computed tomography. J Hand Surg Am. 1991;16:485–492.
• 410 Nakamura P, Imaeda T, Miura T. Scaphoid malunion. J Bone Joint Surg Br. 1991;73:134–137.
• 411 Nanno M, Buford WL Jr, Patterson RM, et al. Three-dimensional analysis of the ligamentous attachments of the second through fifth carpometacarpal joints. Clin Anat. 2007;20:530–544.
• 412 Nanno M, Patterson RM, Viegas SF. Three-dimensional imaging of the carpal ligaments. Hand Clin. 2006;22:399–412.
• 413 Nanno M, Sawaizumi T, Ito H. Dorsal fracture dislocations of the second and third carpometacarpal joints. J Hand Surg Eur Vol. 2007;32:597–598.
• 414 Naranje S, Kotwal PP, Shamshery P, et al. Percutaneous fixation of selected scaphoid fractures by dorsal approach. Int Orthop. 2010;34:997–1003.
• 415 Nattrass GR, King GJ, McMurtry RY, et al. An alternative method for determination of the carpal height ratio. J Bone Joint Surg Am. 1994;76:88–94.
• 416 Navarro AL. Luxaciones del carpo. An Fac Med (Lima). 1921;6:113–141.
• 417 Nguyen Q, Chaudhry S, Sloan R, et al. The clinical scaphoid fracture: early computed tomography as a practical approach. Ann R Coll Surg Engl. 2008;90:488–491.
• 418 Nielsen PT, Hedeboe J. Posttraumatic scapholunate dissociation detected by wrist cineradiography. J Hand Surg Am. 1984;9A:135–138.
• 419 Nijs S, Mulier T, Broos P. Occult fracture of the trapezoid bone: a report on two cases. Acta Orthop Belg. 2004;70:177–179.
• 420 Norman A, Nelson J, Green S. Fractures of the hook of hamate: radiographic signs. Radiology. 1985;154:49–53.
• 421 Nowalk MD, Logan SE. Distinguishing biomechanical properties of intrinsic and extrinsic human wrist ligaments. J Biomech Eng. 1991;113:85–93.
• 422 Obdeijn MC, van der Vlies CH, van Rijn RR. Capitate and hamate fracture in a child: the value of MRI imaging. Emerg Radiol. 2010;17:157–159.
• 423 Oduwole KO, Cichy B, Dillon JP, et al. Acutrak versus Herbert screw fixation for scaphoid non-union and delayed union. J Orthop Surg (Hong Kong). 2012;20:61–65.
• 424 Oh WT, Choi YR, Kang HJ, et al. Comparative outcome analysis of arthroscopic-assisted versus open reduction and fixation of trans-scaphoid perilunate fracture dislocations. Arthroscopy. 2017;33:92–100.
• 425 Oka K, Moritomo H, Murase T, et al. Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis. J Hand Surg Am. 2005;30:1136–1144.
• 426 Oka K, Murase T, Moritomo H, et al. Patterns of bone defect in scaphoid nonunion: a 3-dimensional and quantitative analysis. J Hand Surg Am. 2005;30:359–365.
• 427 Ono H, Gilula LA, Evanoff BA, et al. Midcarpal instability: is capitolunate instability pattern a clinical condition?. J Hand Surg Br. 1996;21:197–201.
• 428 Orlandi D, Fabbro E, Ferrero G, et al. High-resolution ultrasound of the extrinsic carpal ligaments. J Ultrasound. 2012;15:267–272.
• 429 O’Shea K, Weiland AJ. Fractures of the hamate and pisiform bones. Hand Clin. 2012;28:287–300, viii.
• 430 Osterman AL, Seidman GD. The role of arthroscopy in the treatment of lunatotriquetral ligament injuries. Hand Clin. 1995;11:41–50.
• 431 Osti M, Zinnecker R, Benedetto KP. Scaphoid and capitate fracture with concurrent scapholunate dissociation. J Hand Surg Br. 2006;31:76–78.
• 432 Paci GM, Yao J. Surgical techniques for the treatment of carpal ligament injury in the athlete. Clin Sports Med. 2015;34:11–35.
• 433 Pai CH, Wei DC, Hu ST. Carpal bone dislocations: an analysis of twenty cases with relative emphasis on the role of crushing mechanisms. J Trauma. 1993;35:28–35.
• 434 Palmer AK. The distal radioulnar joint. Anatomy, biomechanics, and triangular fibrocartilage complex abnormalities. Hand Clin. 1987;3:31–40.
• 435 Palmer AK, Werner FW. Biomechanics of the distal radioulnar joint. Clin Orthop Relat Res. 1984;26–35.
• 436 Panagis JS, Gelberman RH, Taleisnik J, et al. The arterial anatomy of the human carpus. Part II: The intraosseous vascularity. J Hand Surg Am. 1983;8:375–382.
• 437 Pao VS, Chang J. Scaphoid nonunion: diagnosis and treatment. Plast Reconstr Surg. 2003;112:1666–1676.
• 438 Papaloizos MY, Fusetti C, Christen T, et al. Minimally invasive fixation versus conservative treatment of undisplaced scaphoid fractures: a cost-effectiveness study. J Hand Surg Br. 2004;29:116–119.
• 439 Papilion JD, DuPuy TE, Aulicino PL, et al. Radiographic evaluation of the hook of the hamate: a new technique. J Hand Surg Am. 1988;13:437–439.
• 440 Park MJ. Normal anteroposterior laxity of the radiocarpal and midcarpal joints. J Bone Joint Surg Br. 2002;84:73–76.
• 441 Park MJ. Radiographic observation of the scaphoid shift test. J Bone Joint Surg Br. 2003;85:358–362.
• 442 Park MJ, Cooney WP 3rd, Hahn ME, et al. The effects of dorsally angulated distal radius fractures on carpal kinematics. J Hand Surg Am. 2002;27:223–232.
• 443 Parvizi J, Wayman J, Kelly P, et al. Combining the clinical signs improves diagnosis of scaphoid fractures. A prospective study with follow-up. J Hand Surg Br. 1998;23:324–327.
• 444 Patel NK, Davies N, Mirza Z, et al. Cost and clinical effectiveness of MRI in occult scaphoid fractures: a randomised controlled trial. Emerg Med J. 2013;30(3):202–207.
• 445 Pinder RM, Brkljac M, Rix L, et al. Treatment of scaphoid nonunion: a systematic review of the existing evidence. J Hand Surg Am. 2015;40:1797–1805.
• 446 Platon A, Poletti PA, Van Aaken J, et al. Occult fractures of the scaphoid: the role of ultrasonography in the emergency department. Skeletal Radiol. 2011;40:869–875.
• 447 Pliefke J, Stengel D, Rademacher G, et al. Diagnostic accuracy of plain radiographs and cineradiography in diagnosing traumatic scapholunate dissociation. Skeletal Radiol. 2008;37:139–145.
• 448 Polivy KD, Millender LH, Newberg A, et al. Fractures of the hook of the hamate—a failure of clinical diagnosis. J Hand Surg Am. 1985;10:101–104.
• 449 Potter MQ, Haller JM, Tyser AR. Ligamentous radiocarpal fracture-dislocation treated with wrist-spanning plate and volar ligament repair. J Wrist Surg. 2014;3:265–268.
• 450 Powell JM, Lloyd GJ, Rintoul RF. New clinical test for fracture of the scaphoid. Can J Surg. 1988;31:237–238.
• 451 Prosser AJ, Brenkel IJ, Irvine GB. Articular fractures of the distal scaphoid. J Hand Surg Br. 1988;13:87–91.
• 452 Pruzansky M, Arnold L. Delayed union of fractures of the trapezoid and body of the hamate. Orthop Rev. 1987;16:624–628.
• 453 Raby N. Magnetic resonance imaging of suspected scaphoid fractures using a low field dedicated extremity MR system. Clin Radiol. 2001;56:316–320.
• 454 Ramamurthy C, Cutler L, Nuttall D, et al. The factors affecting outcome after non-vascular bone grafting and internal fixation for nonunion of the scaphoid. J Bone Joint Surg Br. 2007;89:627–632.
• 455 Ramoutar DN, Katevu C, Titchener AG, et al. Trapezium fracture—a common technique to fix a rare injury: a case report. Cases J. 2009;2:8304.
• 456 Rancy SK, Swanstrom MM, DiCarlo EF, et al. Success of scaphoid nonunion surgery is independent of proximal pole vascularity. J Hand Surg Eur Vol. 2018;43:32–40.
• 457 Rand JA, Linscheid RL, Dobyns JH. Capitate fractures: a long-term follow-up. Clin Orthop Relat Res. 1982;209–216.
• 458 Raudasoja L, Rawlins M, Kallio P, et al. Conservative treatment of scaphoid fractures: a follow up study. Ann Chir Gynaecol. 1999;88:289–293.
• 459 Reagan DS, Linscheid RL, Dobyns JH. Lunotriquetral sprains. J Hand Surg Am. 1984;9:502–514.
• 460 Reed DN, Fulcher SM, Harrison SJ. Unstable scaphoid nonunion treatment technique: use of a volar distal radius corticocancellous autograft. Tech Hand Up Extrem Surg. 2012;16:91–94.
• 461 Reichel LM, Bell BR, Michnick SM, et al. Radial styloid fractures. J Hand Surg Am. 2012;37:1726–1741.
• 462 Reigstad O, Grimsgaard C, Thorkildsen R, et al. Long-term results of scaphoid nonunion surgery: 50 patients reviewed after 8 to 18 years. J Orthop Trauma. 2012;26:241–245.
• 463 Reilly BM, Evans AT. Translating clinical research into clinical practice: impact of using prediction rules to make decisions. Ann Intern Med. 2006;144:201–209.
• 464 Rettig ME, Kozin SH, Cooney WP. Open reduction and internal fixation of acute displaced scaphoid waist fractures. J Hand Surg Am. 2001;26:271–276.
• 465 Rettig ME, Raskin KB. Long-term assessment of proximal row carpectomy for chronic perilunate dislocations. J Hand Surg Am. 1999;24:1231–1236.
• 466 Rhemrev SJ, Beeres FJ, van Leerdam RH, et al. Clinical prediction rule for suspected scaphoid fractures. A prospective cohort study. Injury. 2010;41(10):1026–1030.
• 467 Rhemrev SJ, de Zwart AD, Kingma LM, et al. Early computed tomography compared with bone scintigraphy in suspected scaphoid fractures. Clin Nucl Med. 2010;35:931–934.
• 468 Richards RR, Paitich CB, Bell RS. Internal fixation of a capitate fracture with Herbert screws. J Hand Surg Am. 1990;15:885–887.
• 469 Rimington TR, Edwards SG, Lynch TS, et al. Intercarpal ligamentous laxity in cadaveric wrists. J Bone Joint Surg Br. 2010;92:1600–1605.
• 470 Ring D, Jupiter JB, Herndon JH. Acute fractures of the scaphoid. J Am Acad Orthop Surg. 2000;8:225–231.
• 471 Ring D, Lozano-Calderon S. Imaging for suspected scaphoid fracture. J Hand Surg Am. 2008;33:954–957.
• 472 Ring D, Patterson JD, Levitz S, et al. Both scanning plane and observer affect measurements of scaphoid deformity. J Hand Surg Am. 2005;30:696–701.
• 473 Ritt MJ, Berger RA, Bishop AT, et al. The capitohamate ligaments. A comparison of biomechanical properties. J Hand Surg Br. 1996;21:451–454.
• 474 Ritt MJ, Berger RA, Kauer JM. The gross and histologic anatomy of the ligaments of the capitohamate joint. J Hand Surg Am. 1996;21:1022–1028.
• 475 Ritt MJ, Bishop AT, Berger RA, et al. Lunotriquetral ligament properties: a comparison of three anatomic subregions. J Hand Surg Am. 1998;23:425–431.
• 476 Roolker W, Tiel-van Buul MM, Bossuyt PM, et al. Carpal box radiography in suspected scaphoid fracture. J Bone Joint Surg Br. 1996;78:535–539.
• 477 Roolker L, Tiel-van Buul MM, Bossuyt PP, et al. The value of additional carpal box radiographs in suspected scaphoid fracture. Invest Radiol. 1997;32:149–153.
• 478 Roolker W, Tiel-van Buul MM, Ritt MJ, et al. Experimental evaluation of scaphoid X-series, carpal box radiographs, planar tomography, computed tomography, and magnetic resonance imaging in the diagnosis of scaphoid fracture. J Trauma. 1997;42:247–253.
• 479 Rosati M, Parchi P, Cacianti M, et al. Treatment of acute scapholunate ligament injuries with bone anchor. Musculoskelet Surg. 2010;94:25–32.
• 480 Royal College of Radiologists. Making the Best Use of a Department of Clinical Radiology: Guidelines for Doctors. 5th ed. London, UK: Royal College of Radiologists; 2003.
• 481 Rubensson C, Johansson T, Adolfsson L. Tensioning of the radioscaphocapitate and long radio-lunate ligaments for dynamic radiocarpal instability. J Hand Surg Eur Vol. 2018;43:369–374.
• 482 Ruby LK, Leslie BM. Wrist arthritis associated with scaphoid nonunion. Hand Clin. 1987;3:529–539.
• 483 Ruby LK, Stinson J, Belsky MR. The natural history of scaphoid non-union. A review of fifty-five cases. J Bone Joint Surg Am. 1985;67:428–432.
• 484 Ruch DS, Poehling GG. Arthroscopic management of partial scapholunate and lunotriquetral injuries of the wrist. J Hand Surg Am. 1996;21:412–417.
• 485 Russe O. Fracture of the carpal navicular. Diagnosis, non-operative treatment, and operative treatment. J Bone Joint Surg Am. 1960;42-A:759–768.
• 486 Sadowski RM, Montilla RD. Rare isolated trapezoid fracture: a case report. Hand (NY). 2008;3:372–374.
• 487 Saeden B, Tornkvist H, Ponzer S, et al. Fracture of the carpal scaphoid. A prospective, randomised 12-year follow-up comparing operative and conservative treatment. J Bone Joint Surg Br. 2001;83:230–234.
• 488 Sammer DM, Shin AY. Wrist surgery: management of chronic scapholunate and lunotriquetral ligament injuries. Plast Reconstr Surg. 2012;130:138e–156e.
• 489 Sanders WE. Evaluation of the humpback scaphoid by computed tomography in the longitudinal axial plane of the scaphoid. J Hand Surg Am. 1988;13:182–187.
• 490 Sandoval E, Cecilia D, Garcia-Paredero E. Surgical treatment of trans-scaphoid, transcapitate, transtriquetral, perilunate fracture-dislocation with open reduction, internal fixation and lunotriquetral ligament repair. J Hand Surg Eur Vol. 2008;33:377–379.
• 491 Sarrafian SK, Melamed JL, Goshgarian GM. Study of wrist motion in flexion and extension. Clin Orthop Relat Res. 1977;153–159.
• 492 Schadel-Hopfner M, Bohringer G, Junge A. Dislocation of the pisiform bone after severe crush injury to the hand. Scand J Plast Reconstr Surg Hand Surg. 2003;37:252–255.
• 493 Schadel-Hopfner M, Junge A, Bohringer G. Scapholunate ligament injury occurring with scaphoid fracture—a rare coincidence?. J Hand Surg Br. 2005;30:137–142.
• 494 Scheufler O, Andresen R, Radmer S, et al. Hook of hamate fractures: critical evaluation of different therapeutic procedures. Plast Reconstr Surg. 2005;115:488–497.
• 495 Scheufler O, Radmer S, Erdmann D, et al. Therapeutic alternatives in nonunion of hamate hook fractures: personal experience in 8 patients and review of literature. Ann Plast Surg. 2005;55:149–154.
• 496 Schiltenwolf M, Wrazidlo W, Brocai DR, et al. A prospective study of early diagnosis of lunate necrosis by means of MRI. Rofo. 1995;162:325–329.
• 497 Schmitt R, Christopoulos G, Wagner M, et al. Avascular necrosis (AVN) of the proximal fragment in scaphoid nonunion: is intravenous contrast agent necessary in MRI?. Eur J Radiol. 2011;77:222–227.
• 498 Schneider LH, Aulicino P. Nonunion of the carpal scaphoid: the Russe procedure. J Trauma. 1982;22:315–319.
• 499 Schweizer A, Steiger R. Long-term results after repair and augmentation ligamentoplasty of rotatory subluxation of the scaphoid. J Hand Surg Am. 2002;27:674–684.
• 500 Senall JA, Failla JM, Bouffard JA, et al. Ultrasound for the early diagnosis of clinically suspected scaphoid fracture. J Hand Surg Am. 2004;29:400–405.
• 501 Sennwald GR, Zdravkovic V, Kern HP, et al. Kinematics of the wrist and its ligaments. J Hand Surg Am. 1993;18:805–814.
• 502 Sennwald GR, Zdravkovic V, Oberlin C. The anatomy of the palmar scaphotriquetral ligament. J Bone Joint Surg Br. 1994;76:147–149.
• 503 Shahabpour M, De Maeseneer M, Pouders C, et al. MR imaging of normal extrinsic wrist ligaments using thin slices with clinical and surgical correlation. Eur J Radiol. 2011;77:196–201.
• 504 Shen L, Tang J, Luo C, et al. Comparison of operative and non-operative treatment of acute undisplaced or minimally-displaced scaphoid fractures: a meta-analysis of randomized controlled trials. PLoS One. 2015;10:e0125247.
• 505 Shih JT, Lee HM, Hou YT, et al. Results of arthroscopic reduction and percutaneous fixation for acute displaced scaphoid fractures. Arthroscopy. 2005;21:620–626.
• 506 Short WH, Werner FW, Fortino MD, et al. A dynamic biomechanical study of scapholunate ligament sectioning. J Hand Surg Am. 1995;20:986–999.
• 507 Short WH, Werner FW, Fortino MD, et al. Analysis of the kinematics of the scaphoid and lunate in the intact wrist joint. Hand Clin. 1997;13:93–108.
• 508 Short WH, Werner FW, Green JK, et al. Biomechanical evaluation of ligamentous stabilizers of the scaphoid and lunate. J Hand Surg Am. 2002;27:991–1002.
• 509 Short WH, Werner FW, Green JK, et al. The effect of sectioning the dorsal radiocarpal ligament and insertion of a pressure sensor into the radiocarpal joint on scaphoid and lunate kinematics. J Hand Surg Am. 2002;27:68–76.
• 510 Short WH, Werner FW, Green JK, et al. Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: part II. J Hand Surg Am. 2005;30:24–34.
• 511 Short WH, Werner FW, Green JK, et al. Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: part III. J Hand Surg Am. 2007;32:297–309.
• 512 Short WH, Werner FW, Sutton LG. Dynamic biomechanical evaluation of the dorsal intercarpal ligament repair for scapholunate instability. J Hand Surg Am. 2009;34:652–659.
• 513 Singh AK, Davis TR, Dawson JS, et al. Gadolinium enhanced MR assessment of proximal fragment vascularity in nonunions after scaphoid fracture: does it predict the outcome of reconstructive surgery?. J Hand Surg Br. 2004;29:444–448.
• 514 Singh HP, Taub N, Dias JJ. Management of displaced fractures of the waist of the scaphoid: meta-analyses of comparative studies. Injury. 2012;43:933–939.
• 515 Skelly WJ, Nahigian SH, Hidvegi EB. Palmar lunate transtriquetral fracture dislocation. J Hand Surg Am. 1991;16:536–539.
• 516 Skirven T, Trope J. Complications of immobilization. Hand Clin. 1994;10:53–61.
• 517 Slade JF 3rd, Geissler WB, Gutow AP, et al. Percutaneous internal fixation of selected scaphoid nonunions with an arthroscopically assisted dorsal approach. J Bone Joint Surg Am. 2003;85-A (Suppl 4):20–32.
• 518 Slade JF 3rd, Grauer JN, Mahoney JD. Arthroscopic reduction and percutaneous fixation of scaphoid fractures with a novel dorsal technique. Orthop Clin North Am. 2001;32:247–261.
• 519 Slade JF 3rd, Gutow AP, Geissler WB. Percutaneous internal fixation of scaphoid fractures via an arthroscopically assisted dorsal approach. J Bone Joint Surg Am. 2002;84-A(Suppl 2):21–36.
• 520 Slade JF 3rd, Jaskwhich D. Percutaneous fixation of scaphoid fractures. Hand Clin. 2001;17:553–574.
• 521 Slade JF, Lozano-Calderon S, Merrell G, et al. Arthroscopic-assisted percutaneous reduction and screw fixation of displaced scaphoid fractures. J Hand Surg Eur Vol. 2008;33:350–354.
• 522 Slater RR Jr, Szabo RM. Scapholunate dissociation: treatment with the dorsal intercarpal ligament capsulodesis. Tech Hand Up Extrem Surg. 1999;3:222–228.
• 523 Slater RR Jr, Szabo RM, Bay BK, et al. Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model. J Hand Surg Am. 1999;24:232–239.
• 524 Smith DK. Volar carpal ligaments of the wrist: normal appearance on multiplanar reconstructions of three-dimensional Fourier transform MR imaging. AJR Am J Roentgenol. 1993;161:353–357.
• 525 Smith DK. Scapholunate interosseous ligament of the wrist: MR appearances in asymptomatic volunteers and arthrographically normal wrists. Radiology. 1994;192:217–221.
• 526 Smith ML, Bain GI, Chabrel N, et al. Using computed tomography to assist with diagnosis of avascular necrosis complicating chronic scaphoid nonunion. J Hand Surg Am. 2009;34:1037–1043.
• 527 Smith JE, House RH, Gallagher J, et al. The management of suspected scaphoid fractures in English hospitals: a national survey. Eur J Emerg Med. 2016;23:190–193.
• 528 Smith DK, Gilula LA, Amadio PC. Dorsal lunate tilt (DISI configuration): sign of scaphoid fracture displacement. Radiology. 1990;176:497–499.
• 529 Smith P 3rd, Wright TW, Wallace PF, et al. Excision of the hook of the hamate: a retrospective survey and review of the literature. J Hand Surg Am. 1988;13:612–615.
• 530 Soejima O, Iida H, Naito M. Transscaphoid-transtriquetral perilunate fracture dislocation: report of a case and review of the literature. Arch Orthop Trauma Surg. 2003;123:305–307.
• 531 Sokolow C, Saffar P. Anatomy and histology of the scapholunate ligament. Hand Clin. 2001;17:77–81.
• 532 Song D, Goodman S, Gilula LA, et al. Ulnocarpal translation in perilunate dislocations. J Hand Surg Eur Vol. 2009;34:388–390.
• 533 Sotereanos DG, Mitsionis GJ, Giannakopoulos PN, et al. Perilunate dislocation and fracture dislocation: a critical analysis of the volar-dorsal approach. J Hand Surg Am. 1997;22:49–56.
• 534 Souer JS, Rutgers M, Andermahr J, et al. Perilunate fracture-dislocations of the wrist: comparison of temporary screw versus K-wire fixation. J Hand Surg Am. 2007;32:318–325.
• 535 Spiry C, Bacle G, Marteau E, et al. Radiocarpal dislocations and fracture-dislocations: injury types and long-term outcomes. Orthop Traumatol Surg Res. 2018;104:261–266.
• 536 Stein AH Jr. Dorsal dislocation of the lesser multangular bone. J Bone Joint Surg Am. 1971;53:377–379.
• 537 Steinmann SP, Bishop AT. A vascularized bone graft for repair of scaphoid nonunion. Hand Clin. 2001;17:647–653.
• 538 Steinmann SP, Bishop AT, Berger RA. Use of the 1,2 intercompartmental supraretinacular artery as a vascularized pedicle bone graft for difficult scaphoid nonunion. J Hand Surg Am. 2002;27:391–401.
• 539 Stevenson JD, Morley D, Srivastava S, et al. Early CT for suspected occult scaphoid fractures. J Hand Surg Eur Vol. 2012;37:447–451.
• 540 Stimson LA. A Practical Treatise on Fractures and Dislocations. 4th ed. New York: Lea Brothers & Co; 1905.
• 541 Strauch RJ. Scapholunate advanced collapse and scaphoid nonunion advanced collapse arthritis—update on evaluation and treatment. J Hand Surg Am. 2011;36:729–735.
• 542 Straw RG, Davis TR, Dias JJ. Scaphoid nonunion: treatment with a pedicled vascularized bone graft based on the 1,2 intercompartmental supraretinacular branch of the radial artery. J Hand Surg Br. 2002;27:413.
• 543 Stuffmann ES, McAdams TR, Shah RP, et al. Arthroscopic repair of the scapholunate interosseous ligament. Tech Hand Up Extrem Surg. 2010;14:204–208.
• 544 Sugathan HK, Kilpatrick M, Joyce TJ, et al. A biomechanical study on variation of compressive force along the Acutrak 2 screw. Injury. 2012;43:205–208.
• 545 Sulkers GS, Schep NW, Maas M, et al. The diagnostic accuracy of wrist cineradiography in diagnosing scapholunate dissociation. J Hand Surg Eur Vol. 2014;39:263–271.
• 546 Sulkers GS, Schep NW, Maas M, et al. Intraobserver and interobserver variability in diagnosing scapholunate dissociation by cineradiography. J Hand Surg Am. 2014;39:1050–1054.
• 547 Suresh S. Isolated coronal split fracture of the trapezium. Indian J Orthop. 2012;46:99–101.
• 548 Sutton PA, Clifford O, Davis TR. A new mechanism of injury for scaphoid fractures: ‘test your strength’ punch-bag machines. J Hand Surg Eur Vol. 2010;35:419–420.
• 549 Swanson AB. Silicone rubber implants for the replacement of the carpal scaphoid and lunate bones. Orthop Clin North Am. 1970;1:299–309.
• 550 Symes TH, Stothard J. A systematic review of the treatment of acute fractures of the scaphoid. J Hand Surg Eur Vol. 2011;36:802–810.
• 551 Szabo RM, Manske D. Displaced fractures of the scaphoid. Clin Orthop Relat Res. 1988;30–38.
• 552 Szabo RM, Slater RR Jr, Palumbo CF, et al. Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: clinical results. J Hand Surg Am. 2002;27:978–984.
• 553 Tait MA, Bracey JW, Gaston RG. Acute scaphoid fractures: a critical analysis review. JBJS Rev. 2016;4:pii: 01874474-201609000-00004.
• 554 Takami H, Takahashi S, Ando M, et al. Open reduction of chronic lunate and perilunate dislocations. Arch Orthop Trauma Surg. 1996;115:104–107.
• 555 Taleisnik J. The ligaments of the wrist. J Hand Surg Am. 1976;1:110–118.
• 556 Taleisnik J. Classification of carpal instability. Bull Hosp Jt Dis Orthop Inst. 1984;44:511–531.
• 557 Taleisnik J. Triquetrohamate and triquetrolunate instabilities (medial carpal instability). Ann Chir Main. 1984;3:331–343.
• 558 Taleisnik J, Kelly PJ. The extraosseous and intraosseous blood supply of the scaphoid bone. J Bone Joint Surg Am. 1966;48:1125–1137.
• 559 Taljanovic MS, Goldberg MR, Sheppard JE, et al. US of the intrinsic and extrinsic wrist ligaments and triangular fibrocartilage complex–normal anatomy and imaging technique. Radiographics. 2011;31:e44.
• 560 Tambe AD, Cutler L, Murali SR, et al. In scaphoid non-union, does the source of graft affect outcome? Iliac crest versus distal end of radius bone graft. J Hand Surg Br. 2006;31:47–51.
• 561 Tambe AD, Cutler L, Stilwell J, et al. Scaphoid non-union: the role of vascularized grafting in recalcitrant non-unions of the scaphoid. J Hand Surg Br. 2006;31:185–190.
• 562 Tang JB, Ryu J, Omokawa S, et al. Wrist kinetics after scapholunate dissociation: the effect of scapholunate interosseous ligament injury and persistent scapholunate gaps. J Orthop Res. 2002;20:215–221.
• 563 Tang JB, Shi D, Gu YQ, et al. Can cast immobilization successfully treat scapholunate dissociation associated with distal radius fractures?. J Hand Surg Am. 1996;21:583–590.
• 564 Taras JS, Sweet S, Shum W, et al. Percutaneous and arthroscopic screw fixation of scaphoid fractures in the athlete. Hand Clin. 1999;15:467–473.
• 565 Tatebe M, Hirata H, Iwata Y, et al. Limited wrist arthrodesis versus radial osteotomy for advanced Kienböck’s disease—for a fragmented lunate. Hand Surg. 2006;11:9–14.
• 566 Teisen H, Hjarbaek J. Classification of fresh fractures of the lunate. J Hand Surg Br. 1988;13:458–462.
• 567 Teissier J, Escare P, Asencio G, et al. Rupture of the flexor tendons of the little finger in fractures of the hook of the hamate bone. Report of two cases. Ann Chir Main. 1983;2:319–327.
• 568 Temple CL, Ross DC, Bennett JD, et al. Comparison of sagittal computed tomography and plain film radiography in a scaphoid fracture model. J Hand Surg Am. 2005;30:534–542.
• 569 Ten Berg PW, Dobbe JG, Horbach SE, et al. Analysis of deformity in scaphoid non-unions using two- and three-dimensional imaging. J Hand Surg Eur Vol. 2016;41:719–726.
• 570 Thavarajah D, Syed T, Shah Y, et al. Does scaphoid bone bruising lead to occult fracture? A prospective study of 50 patients. Injury. 2011;42:1303–1306.
• 571 Thompson NW, O’Donnell M, Thompson NS, et al. Internal fixation of an isolated fracture of the capitate using the Herbert-Whipple screw. Injury. 2004;35:541–542.
• 572 Thomsen NO. A dorsally displaced capitate neck fracture combined with a transverse shear fracture of the triquetrum. J Hand Surg Eur Vol. 2013;38:210–211.
• 573 Tiel-van Buul MM, Broekhuizen TH, van Beek EJ, et al. Choosing a strategy for the diagnostic management of suspected scaphoid fracture: a cost-effectiveness analysis. J Nucl Med. 1995;36:45–48.
• 574 Tiel-van Buul MM, Roolker W, Broekhuizen AH, et al. The diagnostic management of suspected scaphoid fracture. Injury. 1997;28:1–8.
• 575 Tiel-van Buul MM, van Beek EJ, Borm JJ, et al. The value of radiographs and bone scintigraphy in suspected scaphoid fracture. A statistical analysis. J Hand Surg Br. 1993;18:403–406.
• 576 Tiel-van Buul MM, van Beek EJ, Broekhuizen AH, et al. Diagnosing scaphoid fractures: radiographs cannot be used as a gold standard!. Injury. 1992;23:77–79.
• 577 Tiel-van Buul MM, van Beek EJ, Broekhuizen AH, et al. Radiography and scintigraphy of suspected scaphoid fracture. A long-term study in 160 patients. J Bone Joint Surg Br. 1993;75:61–65.
• 578 Ting MH, Tompson JD, Ek ET. Isolated dislocation of the trapezoid. Hand Surg. 2012;17:391–393.
• 579 Tirman RM, Weber ER, Snyder LL, et al. Midcarpal wrist arthrography for detection of tears of the scapholunate and lunotriquetral ligaments. AJR Am J Roentgenol. 1985;144:107–108.
• 580 Tohyama M, Miya S, Honda Y. Trapezium fracture associated with occult fracture of the proximal pole of the scaphoid. Arch Orthop Trauma Surg. 2006;126:70–72.
• 581 Toker S, Ozer K. Avascular necrosis of the capitate. Orthopedics. 2010;33:850.
• 582 Tomaino MM, King J, Pizillo M. Correction of lunate malalignment when bone grafting scaphoid nonunion with humpback deformity: rationale and results of a technique revisited. J Hand Surg Am. 2000;25:322–329.
• 583 Toms AP, Chojnowski A, Cahir JG. Midcarpal instability: a radiological perspective. Skeletal Radiol. 2011;40:533–541.
• 584 Totterman SM, Miller RJ. Scapholunate ligament: normal MR appearance on three-dimensional gradient-recalled-echo images. Radiology. 1996;200:237–241.
• 585 Tracy CA. Transverse carpal ligament disruption associated with simultaneous fractures of the trapezium, trapezial ridge, and hook of hamate: a case report. J Hand Surg Am. 1999;24:152–155.
• 586 Trezies AJ, Davis TR, Barton NJ. Factors influencing the outcome of bone grafting surgery for scaphoid fracture non-union. Injury. 2000;31:605–607.
• 587 Trumble TE, Bour CJ, Smith RJ, et al. Kinematics of the ulnar carpus related to the volar intercalated segment instability pattern. J Hand Surg Am. 1990;15:384–392.
• 588 Trumble TE, Clarke T, Kreder HJ. Non-union of the scaphoid. Treatment with cannulated screws compared with treatment with Herbert screws. J Bone Joint Surg Am. 1996;78:1829–1837.
• 589 Trumble T, Nyland W. Scaphoid nonunions. Pitfalls and pearls. Hand Clin. 2001;17:611–624.
• 590 Trumble T, Verheyden J. Treatment of isolated perilunate and lunate dislocations with combined dorsal and volar approach and intraosseous cerclage wire. J Hand Surg Am. 2004;29:412–417.
• 591 Ty JM, Lozano-Calderon S, Ring D. Computed tomography for triage of suspected scaphoid fractures. Hand (NY). 2008;3:155–158.
• 592 Unay K, Gokcen B, Ozkan K, et al. Examination tests predictive of bone injury in patients with clinically suspected occult scaphoid fracture. Injury. 2009;40:1265–1268.
• 593 van de Grift TC, Ritt MJ. Management of lunotriquetral instability: a review of the literature. J Hand Surg Eur Vol. 2016;41:72–85.
• 594 van der Molen AB, Groothoff JW, Visser GJ, et al. Time off work due to scaphoid fractures and other carpal injuries in the Netherlands in the period 1990 to 1993. J Hand Surg Br. 1999;24:193–198.
• 595 van Onselen EB, Karim RB, Hage JJ, et al. Prevalence and distribution of hand fractures. J Hand Surg Br. 2003;28:491–495.
• 596 Van Schil P, De Smet C. Simultaneous fracture of carpal scaphoid and trapezium. J Hand Surg Br. 1986;11:112–114.
• 597 Van Tassel DC, Owens BD, Wolf JM. Incidence estimates and demographics of scaphoid fracture in the U.S. population. J Hand Surg Am. 2010;35:1242–1245.
• 598 Vance RM, Gelberman RH, Evans EF. Scaphocapitate fractures. Patterns of dislocation, mechanisms of injury, and preliminary results of treatment. J Bone Joint Surg Am. 1980;62:271–276.
• 599 Vender MI, Watson HK, Black DM, et al. Acute scaphoid fracture with scapholunate gap. J Hand Surg Am. 1989;14:1004–1007.
• 600 Viegas SF, Patterson RM, Ward K. Extrinsic wrist ligaments in the pathomechanics of ulnar translation instability. J Hand Surg Am. 1995;20:312–318.
• 601 Viegas SF, Yamaguchi S, Boyd NL, et al. The dorsal ligaments of the wrist: anatomy, mechanical properties, and function. J Hand Surg Am. 1999;24:456–468.
• 602 Vinnars B, Pietreanu M, Bodestedt A, et al. Nonoperative compared with operative treatment of acute scaphoid fractures. A randomized clinical trial. J Bone Joint Surg Am. 2008;90:1176–1185.
• 603 Volz RG, Lieb M, Benjamin J. Biomechanics of the wrist. Clin Orthop Relat Res. 1980;112–117.
• 604 Waizenegger M, Barton NJ, Davis TR, et al. Clinical signs in scaphoid fractures. J Hand Surg Br. 1994;19:743–747.
• 605 Walsh JJ, Berger RA, Cooney WP. Current status of scapholunate interosseous ligament injuries. J Am Acad Orthop Surg. 2002;10:32–42.
• 606 Walsh JJ 4th, Bishop AT. Diagnosis and management of hamate hook fractures. Hand Clin. 2000;16:397–403.
• 607 Wang YC, Tseng YC, Chang HY, et al. Gender differences in carpal height ratio in a taiwanese population. J Hand Surg Am. 2010;35:252–255.
• 608 Watanabe H, Hamada Y, Yamamoto Y. A case of old trapezoid fracture. Arch Orthop Trauma Surg. 1999;119:356–357.
• 609 Waters PM, Stewart SL. Surgical treatment of nonunion and avascular necrosis of the proximal part of the scaphoid in adolescents. J Bone Joint Surg Am. 2002;84-A:915–920.
• 610 Watson HK, Ashmead D 4th, Makhlouf MV. Examination of the scaphoid. J Hand Surg Am. 1988;13:657–660.
• 611 Watson HK, Ballet FL. The SLAC wrist: scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg Am. 1984;9:358–365.
• 612 Watson HK, Belniak R, Garcia-Elias M. Treatment of scapholunate dissociation: preferred treatment—STT fusion vs other methods. Orthopedics. 1991;14:365–368.
• 613 Watson HK, Rogers WD. Nonunion of the hook of the hamate: an argument for bone grafting the nonunion. J Hand Surg Am. 1989;14:486–490.
• 614 Watson HK, Weinzweig J. Physical examination of the wrist. Hand Clin. 1997;13:17–34.
• 615 Watson HK, Weinzweig J, Zeppieri J. The natural progression of scaphoid instability. Hand Clin. 1997;13:39–49.
• 616 Weber ER. Concepts governing the rotational shift of the intercalated segment of the carpus. Orthop Clin North Am. 1984;15:193–207.
• 617 Weber ER, Chao EY. An experimental approach to the mechanism of scaphoid waist fractures. J Hand Surg Am. 1978;3:142–148.
• 618 Weil WM, Slade JF 3rd, Trumble TE. Open and arthroscopic treatment of perilunate injuries. Clin Orthop Relat Res. 2006;445:120–132.
• 619 Weiss AP. Scapholunate ligament reconstruction using a bone-retinaculum-bone autograft. J Hand Surg Am. 1998;23:205–215.
• 620 Weiss AP, Sachar K, Glowacki KA. Arthroscopic debridement alone for intercarpal ligament tears. J Hand Surg Am. 1997;22:344–349.
• 621 Werner FW, Palmer AK, Fortino MD, et al. Force transmission through the distal ulna: effect of ulnar variance, lunate fossa angulation, and radial and palmar tilt of the distal radius. J Hand Surg Am. 1992;17:423–428.
• 622 Whalen JL, Bishop AT, Linscheid RL. Nonoperative treatment of acute hamate hook fractures. J Hand Surg Am. 1992;17:507–511.
• 623 Wharton DM, Casaletto JA, Choa R, et al. Outcome following coronal fractures of the hamate. J Hand Surg Eur Vol. 2010;35:146–149.
• 624 Wheatley MJ, Finical SJ. A 32-year follow-up of lunate excision for Kienböck’s disease: a case report and a review of results from excision and other treatment methods. Ann Plast Surg. 1996;37:322–325.
• 625 Whipple TL. The role of arthroscopy in the treatment of wrist injuries in the athlete. Clin Sports Med. 1992;11:227–238.
• 626 Whipple TL. The role of arthroscopy in the treatment of scapholunate instability. Hand Clin. 1995;11:37–40.
• 627 Wiesler ER, Chloros GD, Kuzma GR. Arthroscopy in the treatment of fracture of the trapezium. Arthroscopy. 2007;23:1248.e1–e4.
• 628 Wildin CJ, Bhowal B, Dias JJ. The incidence of simultaneous fractures of the scaphoid and radial head. J Hand Surg Br. 2001;26:25–27.
• 629 Williams CS, Gelberman RH. Vascularity of the lunate. Anatomic studies and implications for the development of osteonecrosis. Hand Clin. 1993;9:391–398.
• 630 Wilton TJ. Soft-tissue interposition as a possible cause of scaphoid non-union. J Hand Surg Br. 1987;12:50–51.
• 631 Wintman BI, Gelberman RH, Katz JN. Dynamic scapholunate instability: results of operative treatment with dorsal capsulodesis. J Hand Surg Am. 1995;20:971–979.
• 632 Witvoet J, Allieu Y. Recent traumatic lesions of the semilunar bone. Rev Chir Orthop Reparatrice Appar Mot. 1973;59 Suppl-1:98–125.
• 633 Wolf JM, Dawson L, Mountcastle SB, et al. The incidence of scaphoid fracture in a military population. Injury. 2009;40:1316–1319.
• 634 Wolfe SW, Crisco JJ. Mechanical evaluation of the scaphoid shift test. J Hand Surg Am. 1994;19:762–768.
• 635 Wolfe SW, Gupta A, Crisco JJ 3rd. Kinematics of the scaphoid shift test. J Hand Surg Am. 1997;22:801–806.
• 636 Wolfe SW, Neu C, Crisco JJ. In vivo scaphoid, lunate, and capitate kinematics in flexion and in extension. J Hand Surg Am. 2000;25:860–869.
• 637 Wollstein R, Wei C, Bilonick RA, et al. The radiographic measurement of ulnar translation. J Hand Surg Eur Vol. 2009;34:384–387.
• 638 Wong TC, Ip FK. Minimally invasive management of trans-scaphoid perilunate fracture-dislocations. Hand Surg. 2008;13:159–165.
• 639 Wong K, von Schroeder HP. Delays and poor management of scaphoid fractures: factors contributing to nonunion. J Hand Surg Am. 2011;36:1471–1474.
• 640 Wright TW, Dobyns JH, Linscheid RL, et al. Carpal instability non-dissociative. J Hand Surg Br. 1994;19:763–773.
• 641 Wyrick JD, Youse BD, Kiefhaber TR. Scapholunate ligament repair and capsulodesis for the treatment of static scapholunate dissociation. J Hand Surg Br. 1998;23:776–780.
• 642 Yamaguchi H, Takahara M. Transradial styloid, transtriquetral perilunate dislocation of the carpus with an associated fracture of the ulnar border of the distal radius. J Orthop Trauma. 1994;8:434–436.
• 643 Yamazaki H, Kato H, Nakatsuchi Y, et al. Closed rupture of the flexor tendons of the little finger secondary to non-union of fractures of the hook of the hamate. J Hand Surg Br. 2006;31:337–341.
• 644 Yanni D, Lieppins P, Laurence M. Fractures of the carpal scaphoid. A critical study of the standard splint. J Bone Joint Surg Br. 1991;73:600–602.
• 645 Yao J, Zlotolow DA, Lee SK. Scapholunate axis method. J Wrist Surg. 2016;5:59–66.
• 646 Yardley MH. Upper limb fractures: contrasting patterns in Transkei and England. Injury. 1984;15:322–323.
• 647 Yin ZG, Zhang JB, Kan SL, et al. Diagnosing suspected scaphoid fractures: a systematic review and meta-analysis. Clin Orthop Relat Res. 2010;468:723–734.
• 648 Yip HS, Wu WC, Chang RY, et al. Percutaneous cannulated screw fixation of acute scaphoid waist fracture. J Hand Surg Br. 2002;27:42–46.
• 649 Yoshihara M, Sakai A, Toba N, et al. Nonunion of the isolated capitate waist fracture. J Orthop Sci. 2002;7:578–580.
• 650 You JS, Chung SP, Chung HS, et al. The usefulness of CT for patients with carpal bone fractures in the emergency department. Emerg Med J. 2007;24:248–250.
• 651 Youm Y, McMurthy RY, Flatt AE, et al. Kinematics of the wrist. I. An experimental study of radial-ulnar deviation and flexion-extension. J Bone Joint Surg Am. 1978;60:423–431.
• 652 Zaidemberg C, Siebert JW, Angrigiani C. A new vascularized bone graft for scaphoid nonunion. J Hand Surg Am. 1991;16:474–478.
• 653 Zdravkovic V, Sennwald GR, Fischer M, et al. The palmar wrist ligaments revisited, clinical relevance. Ann Chir Main Memb Super. 1994;13:378–382.
• 654 Ziter FM Jr. A modified view of the carpal navicular. Radiology. 1973;108:706–707.
• 655 Zoltie N. Fractures of the body of the hamate. Injury. 1991;22:459–462.