Radial head fractures are common (approximately 20% of acute elbow injuries) and occur as a result of a fall onto an outstretched hand with the elbow in extension and wrist in pronation. The force is transmitted as an axial load through the wrist and through the radial head. They are more common in females and peak in the 4th decade.
The classification of radial head fractures is based a description of radial head fractures by Mason, but later modified by Broberg & Morrey and Hotchkiss . The classification can be used in the decision making about which fractures may benefit from replacement of the radial head.
With respect to the above classification, radial head fixation is reserved for Mason Type II fractures and is the lead author’s default method of management for fractures that are significantly displaced, and/or cause a mechanical block to motion and are potentially reconstructible. In younger patients and those with better bone quality, it is possible to anatomically reduce and fix comminuted fractures. If the fracture is reducible and a stable fixation is possible, an attempt at fixation is a reasonable option even if there is little residual soft tissue attachment to the fracture fragments.
The aim of fixation is to restore the radial height and joint congruity and confer stability to the elbow joint. This includes range of motion in the flexion-extension arc as well as prono-supination.
It must be appreciated by those treating these fractures that radial head trauma can range from a simple, isolated fracture to complex fracture patterns with significant associated soft tissue components such as :
Lateral collateral ligament (LCL) injury. The most common association from axial loading in supination
Medial collateral ligament (MCL) injury .Occurring due to axial & valgus force
Combination LCL & MCL injuries. These are a higher energy and sit at the severe end of spectrum
Coronoid fractures. Occurring due to axial load in extension +/- dislocation
Fracture dislocation. These may result in “terrible triad” injuries of elbow dislocation, radial head fracture and coronoid fracture.
Essex-Lopresti injury. An associated distal radioulnar joint injury with rupture of the interosseous membrane
Khalfayan et al. retrospectively compared Mason Type-2 fractures treated non-operatively or by open reduction and internal fixation and reviewed outcomes at a mean of 1.5 years. Clinical outcomes were significantly better in the open reduction and internal fixation group, with almost a 90% rate of good to excellent results against approximately 40% in the nonoperative group.
Wu et al. also demonstrated good outcomes with this method of fixation and showed no significant difference in Mayo Elbow Performance scores (MEPs) nor range of movement between the tripod technique, radial head arthroplasty and plate fixation techniques.
Complications rates reported were highest after plate fixation, followed by screw fixation and arthroplasty. Of note, the authors reported over a 30% revision rate for patients undergoing radial head plating against just over 6% after “tripod” screw fixation.
However, risks of major complications are higher in terrible triad and complex fractures with associated instability. Watters et al reported a revision rate of almost 30% in patients undergoing either plate fixation or radial head arthroplasty in the treatment of these terrible triad injuries.
The Medartis Cannulated Compression Screw (CCS) has several design features of note that aid radial head fracture fixation.
The screws are made of titanium and come in a range of diameters and lengths to allow great flexibility in addressing complex fracture patterns. With respect to radial head fractures, the relevant screw diameters are the 3.0 and 2.2mm headless CCS screws, although the range includes diameters from 2.7mm up to 7.0mm. These come in either a short or long distal thread option and range from 10-30mm in 1mm increments for the 2.2 and 3.0mm screws. The 3.0mm screws also have lengths from 30-40mm in 2mm increments. The screws also have self cutting threads so the screws can be applied once the Kirschner wires have been sited appropriately. The benefit of not having to over drill minimises the risk of loss of reduction involved in this step. There is no plate option with this set.
Open Reduction and Internal Fixation (ORIF)
For Mason type II and type III fractures that are amenable to fixation, the radial head fragments can be fixed using cannulated headless screws. This typically consists of radial head fractures that involve 2-3 main fragments, are significantly displaced or cause a mechanical block either at the proximal radioulnar or radiocapitellar joint.
Ring et al. suggested that open reduction and internal fixation should be reserved for fractures with three or less articular fragments. Fixation of unstable multifragmentary fracture patterns involving more than three fragments risks failure of fixation, fragment nonunion, avascular necrosis and unpredictable range of motion.
SYMPTOMS & EXAMINATION
Radial head fractures present with pain on the lateral aspect of the elbow. There may be associated swelling and limitation in flexion/extension as well as pronation/supination.
It is important to ascertain whether there is a true mechanical block in pronation/supination. Once the initial pain has settled, patients may notice a click.
Patients complain of tenderness on the lateral aspect of the elbow. If there is subluxation/dislocation of the radial head fragment, it can to be palpated posterolaterally. Passive pronation/supination of the wrist can help localise the radiocapitellar articulation.
In an acute presentation, it may be difficult to examine the elbow further due to pain. An aspiration of the haemarthrosis and injection of local anaesthetic to the joint can relieve pain to allow assessment for a mechanical block and stability.
When suspecting an Essex-Lopresti injury, assessment of the distal radioulnar joint (DRUJ) is required to confirm the diagnosis. Distal radioulnar ballotment test is performed with the elbow flexed to 90 degrees and resting on the table. It is assessed with the wrist in pronation and supination, whereby a translational force is applied across the DRUJ to assess the stability. A test is positive when pain is elicited or there is increased translation in comparison to the contralateral side. The interosseous membrane can palpated to elicit tenderness.
IMAGING
Plain AP and lateral radiographs of the elbow joint are required to confirm the fracture and the level of displacement. If an occult fracture is suspected, anterior and posterior fat pad signs can aid in diagnosis. A radiograph of the wrist is indicated if suspecting an Essex-Lopresti injury.
With comminuted radial head fractures, a CT of the elbow is helpful in surgical planning as well as delineating associated injuries.
Classification
The classification of radial head fractures is based a description of radial head fractures by Mason, but later modified by Broberg & Morrey and Hotchkiss . The classification is as follows and can be used in the decision making about which fractures may benefit from replacement of the radial head :
Type I – Undisplaced or minimally displaced (<2mm) or marginal lip fracture with no mechanical block
Type II – Displaced (>2mm) or angulated fracture, with mechanical block, without severe comminution
Type III – Comminuted and displaced fracture, not amenable to fixation
Type IV – Radial head fracture with associated dislocation
NON-OPERATIVE TREATMENT
In Mason Type I fractures, isolated, undisplaced fractures are treated conservatively with temporary sling immobilisation and when comfortable, active ROM exercises are commenced under the guidance of physiotherapy services.
ALTERNATIVE SURGICAL MANAGEMENT
Open reduction and internal fixation using radial head plates
Radial head fractures can be fixed using radial head plates. This method of fixation should be included in the armamentarium of complex radial head/neck fractures. Indications include if the fracture extends into the radial neck.
Disadvantages of this method of fixation is that as the plate sits on the radial neck, it can impinge on the annular ligament. This can affect pronosupination and result in stiffness and loss of range on motion in this arc of movement. In reality, this method of fixation is reserved for complex fractures where risk or residual stiffness is greater.
Radial head replacement
Radial head replacement is used in the armamentarium for radial head fracture management. They are reserved for:
Comminuted Mason type III fractures that are unreconstructible
Mason type IV fractures where residual instability cannot be completely resolved by addressing other associated injuries
Essex-Lopresti injuries (as previously described)
Partial Excision
For isolated Mason type II and type III fractures, if the fragments are not amenable to fixation, it is an option to excise these fragments. Figures quoted range from 25-33% of the articular surface can be excised. However, it is important to exclude associated injuries in this case and to ensure that the elbow is stable when assessed through a full range of movement.
Radial head excision
For Mason type III fractures that are not amenable to fixation, excision of the radial head can be performed.
Although reported outcomes in the literature have been good, it does alter elbow biomechanics. As a result, this procedure is largely reserved for patients of low demand or for failed conservative management.
It can result in ulnohumeral arthritis, valgus instabilty, proximal radioulnar instability and tardy ulna nerve dysfunction.
It is contraindicated in Essex-Lopresti injuries and in elbow injuries with associated injuries due to the risk of residual instability.
CONTRAINDICATIONS
Headless screw fixation is best used for fracture patterns involving 2-3 major fragments. Evidence suggests fractures with great comminution have a greater rate of failure and worse outcome. Consideration has to be given to either fixation using a radial head plate or radial head replacement in these cases.
Age is not usually a contra-indication per se, but in osteoporotic fractures, the bone quality and level of comminution determine the viability of headless screw fixation. As with all intra-articular fractures, the aim of surgery is to restore anatomy using a reliable and stable method to restore function.
A lateral radiograph showing the position is maintained.Although the anterior screw looks prominent, this is again likely to be projectional as the x-ray beam would need to be orthogonal to the screw to get a true appreciation as to the screws precise location.As it sits at the margin of the radial head, it is not likely to cause irritation at the radio-capitellar articulation even if fractionally prominent.If the screw does irritate the proximal radial notch of the ulna, there is likely associated crepitus and pain.Note that over time, screws can occasionally back out 1-2mm and irritate the joint surface. It is important to be open to this problem as the metalwork may need to be removed once the bone has healed.
This is an early AP/oblique radiograph of the elbow post fixation. This fixation is holding well.Although the most superior screw (A) looks prominent, this is likely to be projectional and not likely to be irritating the joint either way.As noted from the intra-operative reduction, the fracture is not quite anatomically reduced at the radial neck (B), but likely due to some comminution and accpetance of the final position intra-operatively. It is not likely to be causing a clinical problem.
