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Internal fixation of fracture dislocation of the navicular

    Overview

    Learn the Internal fixation of fracture dislocation of the navicular surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Internal fixation of fracture dislocation of the navicular surgical procedure.
    The navicular is the keystone of the medial longitudinal arch and forms part of a “ball and socket” arrangement with the head of the talus, termed by some as the coxa pedis. Together with the talus, three cuneiforms and the medial three rays, the navicular is a key component of the medial column of the foot with the lateral column comprising of the calcaneum, cuboid and the lateral two rays. Owing to its intimate relationships with its surrounding architecture, the navicular is rarely injured in isolation, especially in higher energy injuries.
    The talonavicular joint, together with the calcaneo-cuboid joint, forms the transverse tarsal joint, crucial for effective gait – absorbing energy in heel strike and stiffening to aid in propulsion. The combination of these two joints is commonly referred to the Chopart joint. Acute, traumatic fractures of the navicular are relatively uncommon with an incidence of 1.7/100,000/year. In addition, the severity of injuries to the navicular lie on a spectrum dependent upon the amount and nature of the energy imparted across the bone. Injuries range from simple ligamentous avulsions associated with ankle sprains through to crush injuries not only involving the navicular but also the cuboid and have been comprehensively classified into five groups in a recent paper from the Sheffield Foot and Ankle Unit. These latter, high-energy injuries have been shown to correlate with significant long-term morbidity and adverse function especially in the multiply injured patient. Failure to restore the anatomic relationships of the bony components within both columns, together with their relative column length, can result in significant morbidity. Navicular fractures can be subtle and diagnosis is frequently delayed, either through inadequate imaging or the presence of other significant, distracting injuries in the multiply injured patient.
    One final crucial element to navicular fractures lies in common with fractures of the talus, namely that the navicular has a poor vascular supply. The bone receives blood via radial vessels leaving the central area prone to avascular change. These radial vessels emirate from both the dorsalis pedis and posterior tibial arteries with an indirect supply through the tendon insertion of the posterior tibial tendon. This means that, with injury, the navicular is prone to avascular necrosis and collapse.

    Indications

    INDICATIONS
    An acute, unstable, displaced fracture of the navicular with resultant disruption to the medial column of the foot. Any irreducible fracture-dislocation of the navicular where the skin is threatened or is open is an absolute, and urgent, indication to urgent reduction and either definitive internal or temporising external fixation.
    SYMPTOMS & EXAMINATION
    The classic symptoms and signs in an unstable navicular fracture are pain, significant swelling, deformity and an inability to bear weight. The mechanism of injury usually involves more energy than an injury to the tarsometatarsal (Lisfranc) joint and thus is seen in falls from a height, road traffic collisions with footwell impaction and crush injuries.
    The patient often indicates the source of the pain to lie in the dorsum of the midfoot. Swelling is usual and persistent. There may be blanching of the skin owing to pressure on the skin from extruded bony fragments. On the sole of the foot, there may be a characteristic D-shaped bruise under the medial arch that is also seen in tarsometatarsal injuries. With knowledge of the surface anatomy of the bones and joints of the foot, tenderness can be localised to specific parts of the tarsometatarsal and transverse tarsal complexes. It is important to assess the whole of the medial and lateral column for tenderness as it is likely that there will be injury to the lateral column in all but the lowest energy navicular fractures. In some instances, the joints may be subluxatable and in fixed dislocations, the soft tissue envelope may be threatened as a high proportion of these injuries are open.
    Clearly, the neurovascular status of the foot needs to be assessed.
    IMAGING
    Plain radiographic imaging is the initial mode of imaging. Three views are taken: dorso-plantar, oblique and lateral. Weight-bearing views are seldom helpful as, unlike in tarsometatarsal injuries, patients usually struggle to bear weight. My personal view, and that of my colleagues in Sheffield, is that a CT scan is mandatory and aids in fracture classification. This helps detail the injured structures and aids in planning surgical approach and methods of fixation. CT demonstrates small bony avulsion fracture fragments, subtle dislocation, and crushing guiding the surgeon to restore column length.
    ALTERNATIVE OPERATIVE TREATMENT
    Unlike in tarsometatarsal injuries, there is no literature contradicting navicular fracture and Chopart reconstructive surgery versus primary fusion of affected joints. There are far fewer papers in the literature on this subject with many pre-dating the era of CT scanning and often advocating K-wire and casting techniques. Given the subtle nature of the complexity of these injuries, older papers relying upon inferior quality radiographic imaging must have missed the subtleties of many injuries.

    My view is that these injuries respond best to accurate internal fixation and restoration of foot anatomy. At the very least, this permits the surgeon to perform reconstructive surgery at a later date with the foot resembling a more normal shape. The following principles from a seminal paper by Pinney & Sangeorzan are worth adhering to when considering fixation:
    •Maintain appropriate medial and lateral column length
    •Maintain appropriate relationship between the forefoot and the hindfoot
    •Preserve talonavicular joint function
    •Preserve the fourth and fifth tarsometatarsal joints (Cubo-metatarsal joints)
    •Use stable fixation to maintain anatomic reductions
    As in tarsometatarsal injuries, there is a limited role for percutaneous fixation for these injuries because the subtle nuances of achieving accurate reduction can be difficult to appreciate under fluoroscopic views alone.
    Stable fixation means the use of sufficiently robust hardware such as plates and screws. In my opinion, the role of K-wires are limited to:
    1 Intra-operative reduction tools.
    2 Occasional stabilisation of the lateral column of the foot.
    3 In damage limitation surgery for polytrauma.
    NON-OPERATIVE MANAGEMENT
    In the very frail, elderly patients, there may be a role for simple casting techniques as a treatment.
    CONTRAINDICATIONS
    Be very aware of the red, swollen and unstable foot with little pain. This presentation should raise the suspicion of a neuropathic foot undergoing a Charcot process.
    Open incisions to the traumatised foot in the presence of diabetes, vascular disease or metabolic compromise from steroid treatment are relative contra-indications for surgical intervention. Previous fasciotomy incisions made for compartment syndrome can also scupper definitive internal fixation.

    Setup

    The patient is positioned supine on the operating table and may require a sandbag under the ipsilateral buttock so that the foot points vertically towards the ceiling. Fluoroscopy should be available with an image intensifier and a trained radiographer. An examination under anaesthesia can be performed to confirm the surgical approach. Throughout the procedure, I find it best if I can readily view all three planes of the CT scans on a monitor particularly when trying to reduce and lag key fracture fragments.

    Appropriate antibiotics are administered and, my preference is to apply a thigh tourniquet and exclusion drape. The limb is prepared with Chlorhexidine from toes to tourniquet.

    Operation

    Plain radiographic assessment of the foot and ankle
    In this case, a 19-year old male sustained a closed injury to his right foot having fallen 6 feet off a garden wall and twisting his foot on landing. He presented with a swollen, painful foot through which he found it impossible to bear weight. On the lateral radiographic view, the navicular fracture is clearly seen with a significant dorsal bone fragment and disruption of both the talonavicular and naviculo-cuneiform joint.

    CT is mandatory assessment to determine fracture anatomyThe sagittal CT slices show the large dorsal bone fragment and the disruption of the talonavicular and naviculocuneiform joints. Note the fracture line at this level runs in a medio-lateral plane.

    Also note, as an incidental finding, the coalition between the anterior process of the calcaneus and the navicular.

    On this axial section through the foot, the fracture line is now in the sagittal plane. Quite often the energy creates a tri-partite split in the navicular akin to a “Mercedes-Benz” logo with one (or both) of the dorsal fragments subluxating. This makes the fracture conform to the Type 4 group within the Sheffield classification system.
    There is no apparent injury to the lateral column.
    With this information, the surgical strategy is to reduce and fix the navicular, stabilise the talonavicular joint and naviculo-cuneiform joint and restore stability to the medial column of the foot.

    The surface anatomy is marked on the skin including the navicular tubercleI find it best to mark out the easy surface landmarks of the underlying bony anatomy. Hence I mark out the ankle joint from medial malleolus and tracking laterally (the dotted line in the illustration). Then I locate the tubercle of the navicular and mark it with a cross. The lateral extent of the navicular is then easily identified because it lies immediately distal and dorsal to the sinus tarsi. Thus the dorsal boundaries of the bone can be marked.

    A dorsal skin incision is made at the point of the sagittal splitHaving established the boundaries of the navicular, I try and mark a longitudinal approach to lie close to the where the dorsal sagittal split in the navicular will lie in order to minimise periosteal stripping from the navicular (Remember that the injured navicular is prone to avascular necrosis). A more classical textbook approach would be to employ a “utility” longitudinal incision mid-way between the tendons of tibialis anterior and posterior, but in my experience this rarely affords good visualisation of the more dorsally orientated fracture fragments. Clearly, any approach needs to respect the neurovascular bundle which, in this case, will lie immediately (1cm or so) lateral to the incision.

    The tendon of tibialis anterior is exposed and protectedAfter incising the skin, the deeper layers are incised with sharp dissection and care with achieving haemostasis. As in many midfoot fractures and fracture-dislocations, a lot of the dissection has been done by the energy in the initial injury.
    In this photograph, the tendon of tibialis anterior is clearly visible crossing the wound and medial to it, the soft tissue disruption is evident.

    The fracture fragments are mobilisedIn this image, I have introduced a McDonald tool into the transverse extension of the fracture line to mobilise the fracture.

    The dorsally displaced fragment can be clearly seen here with retraction on the tibialis anterior tendon.

    Wound closureThe subcutaneous tissues are closed with 2/0 vicryl and the skin closed with 3/0 monocryl. Note the closure of the stab incisions to allow the passage of the pointed tenaculum forceps.

    Application of Plaster of Paris slabsThe wound is dressed with Jelonet dressings and dressing gauze. Orthopaedic wool is applied circumferentially from the level of the tibial tubercle to the base of the toes followed by plaster of Paris slabs in a back slab and stirrup conformation. The plaster slabs are secured with a crepe bandage. I rest the patient’s foot on my belly in a plantigrade position whilst the cast cures.

    Pointed tenaculum forceps are applied to reduce the transverse splitA large pointed tenaculum forceps is useful to achieve reduction of the fracture. I prefer not to crush the skin and make a small skin incision at each end of the jaws to allow the instrument to be applied directly to the bone. In this case the forceps is applied dorso-laterally to plantar-medially to reduce the transverse plane fracture line first.

    A guide wire is then passed from the dorsolateral fragment into the plantar fragmentA guide wire is then passed from the dorsolateral fragment into the plantar fragment. In this case, the wire is for use with a Standard Acutrak 2 screw. This headless screw system is great for these fractures because it allows the surgeon to apply a dorsal plate overlying the screw. As all trauma surgeons would appreciate, if a standard screw with a head was used, one could guarantee that it would inevitably obstruct the optimal positioning of the plate!

    The temporary reduction is checked fluoroscopically in AP, lateral and oblique planesAs with introduction of any guide wire, its position needs to be checked. I check this with 3 views – a dorso-plantar view, an oblique mid foot view and a lateral view. The dorso-plantar view gives the best views of achieving congruency of the talonavicular joint and the medial naviculo-cuneiform joint. The oblique view shows the middle & lateral naviculo-cuneiform joints as well as the inter cuneiform joints and, of course, both of these views show the tarsometatarsal joints well. The lateral is good at showing the reduced dorsal fragments and talonavicular joint restoration and for making sure that the hardware is not passing into any joints.
    In this photograph I am demonstrating how to obtain the lateral view with the image intensifier.

    The lateral view from the intensifier confirms accurate reduction of the fracture line and suitable positioning of the guide wire.

    The length of the guide wire is measured and screw length determinedThe guide wire is measured to determine the appropriate screw length and then over-drilled.

    The lag screw is then inserted across the transverse fracture line and the position checked with fluoroscopyThe lateral image intensifier view confirms the well-seated Acutrak 2 headless screw.

    The sagittal split was reduced and held with a K-wire and the position checked fluoroscopicallyThe next step in this procedure was to reduce the sagittal split in the navicular. With manual reduction, the smaller dorso-medial fragment was temporarily held with another guide wire. Again the positioning of the guide wire is checked on the image intensifier.

    A lag screw was applied across the sagittal splitIn this instance a 4mm Stryker Asnis screw was used to compress the fracture line.

    The foot is then assessed for stability of the navicular-cuneiform and talo-navicular joints.With a McDonald tool retracting the skin edge, it is clear to see the medial cuneiform (A) and the navicular (B) together with the headless screw. It can be appreciated that there is incongruence of the medial naviculo-cuneiform joint which is more apparent with motion applied across this line of joints and also the talonavicular joint.
    In my experience, simple lagged screws across these fractures are not sufficiently robust fixation and further neutralisation with bridge plating is warranted in order to provide stability to the fixation.

    Bridge plating from the neck of the talus to the medial cuneiform protects the lag screws fixation Using a Zimmer Biomet Universal rear foot locking plate of suitable length to bridge from the neck of the talus to the medial cuneiform, the plate is first applied to the neck of the talus. For most individuals, the Titan 37mm plate is the perfect length to span from talus to medial cuneiform, but the 50mm and 66mm plates can also be used for longer spans of bridging. The Zimmer Biomet rear foot plating system uses a fixed angled locking sleeve (A) with a 2.7mm drill. Initially, I tend to secure the plate with a non-locking screw to the talus as this allows me to adjust the rotation of the plate pivoting around the index screw. Once one screw is in situ, the surgeon reduces the foot onto the plate by pushing on the forefoot (B). It may require the plate to be contoured slightly with plate benders in order to seat the plate in an optimal position. When it is clear that the two screw holes in the distal portion of the plate overly the medial cuneiform, the talus screw can be tightened and locking screws can be applied to the remaining holes overlying the talus and medial cuneiform. There is no need to pass screws into the navicular.

    The final position of the plate can be appreciated in this photograph noting the absence of screws in the middle two screw holes overlying the navicular.

    The position of the plate and length of screws are checked fluoroscopicallyThe position is checked on the image intensifier with this oblique image showing the bend in the plate to contour it and the position of the locking screws within the neck of the talus and the medial cuneiform. A satisfactory reduction has been achieved.

    The lateral image intensifier view shows the reduction of the navicular, restoration of the talonavicular and naviculo-cuneiform joints, making sure that none of the hardware penetrates the joints.

    Post Operative

    The patient is kept in the below the knee back slabs for the first two weeks after surgery. At two weeks, the wounds are inspected and re-dressed and a complete, lightweight below-the-knee cast is applied for a further four weeks. Weight bearing is not permitted for the first six weeks after surgery and in my practice, rivaroxaban is prescribed for this duration to prevent thrombo-embolic events.
    At six weeks, the patient can commence weight bearing in a walker boot which can be removed for sleeping. Basic ankle range of motion exercises are encouraged.
    At twelve weeks, the foot is assessed radiographically with standing views in three planes before abandoning further immobilisation. As the talonavicular joint has been bridged, it is necessary to plan for elective removal of this hardware soon as union has occurred. In my practice, the best way to assess for union is to further image with CT. This usually occurs approximately 4 months after fixation. Once union is confirmed, it is important to remove the plate bridging the navicular as soon as possible so that motion can be restored to the talonavicular joint. Physiotherapy is of great help in restoring the mobility of this joint.

    Recommended Reading

    Fractures of the tarsal bones. Pinney SJ, Sangeorzan BJ Orthop Clin North Am 2001; 32(1): 21-33.
    This seminal paper is the first detailed account of the principles of managing tarsal trauma especially with regard to fractures of the navicular and the cuboid. The tenets of reconstructing and restoring the absolute and relative lengths of the columns of the foot are brilliantly described. This paper is a MUST read for all trauma surgeons interested in foot and ankle trauma surgery and has guided and influenced my thoughts on the subject.
    Displaced intra-articular fractures of the tarsal navicular. Sangeorzan BJ, Benirschke SK, Mosca V et al. J Bone Joint Surg 1989; 71A: 1504-1510.
    This key paper from the 1980s was the first to try and categorise fractures of the navicular. The paper was written before CT was in regular use for defining fracture pathoanatomy and only focuses on those fractures that were fixed. Nonetheless, it was clear from the three fracture grades in this paper, that increasing comminution of the navicular led to deteriorating outcomes. Additionally, the better the quality of reduction, the better the outcome.
    Minifragment plate fixation of high-energy navicular body fractures. Evans J, Beingessner DM, Agel J et al. Foot Ankle Int 2011; 32(5): 485-492.
    Two dozen patients from a trauma centre were assessed for radiographic complications after navicular fracture fixation. Although one in eight patients had broken hardware, only about a fifth of patients needed hardware removal. Less than a fifth of patients ended up with post-traumatic arthrosis and the incidence of avascular necrosis was less than one in twenty.
    A new and reliable classification system for navicular fractures and associated injuries to the midfoot complex. MJ Petrie, Blakey C, Chadwick C et al. Bone Joint J 2018; 100B: 176-182.
    This is the largest series of navicular fractures in the English literature and offers a comprehensive classification of all navicular fractures in five groups ranging from simple avulsions through to complex bi-column crush injuries. In addition, it highlights the need to be aware of medial column injuries propagating through the Lisfranc ligament. It offers a tool for surgeons to guide what features to look for on CT to determine signs of instability and how these injuries can be fixed.

    Reference

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