Medial Condyle fractures

Rare fracture (1-2% of all elbow injuries) with high complication rate (33%),

Mechanism of injury

Valgus force on an extended elbow, force transmission via the olecranon or coronoid process into the medial condyle. Alternatively, avulsion the condyle from overpull of the flexors of the forearm.

Classification

Bensahel:

Type 1 - Minimally displaced
Type 2 - Displaced but minimally rotated (>2mm intraarticular displacement)
Type 3 - Significant displacement or rotation.

Radiographs

Diagnosis may be obvious on plain films.

It is important to differentiate a medial condylar fracture from a fracture of the medial epicondyle. This may not be easy in the young child.

Medial epicondylar fractures often are associated with elbow dislocations, usually posterolateral, and elbow dislocations are rare before ossification of the medial condylar epiphysis begins.
With medial condylar physeal fractures, the elbow tends to subluxate posteromedially because of the loss of trochlear stability.
Any metaphyseal ossification with the epicondylar fragment suggests the presence of an intraarticular fracture of the medial condyle.
A positive fat pad sign indicates that the injury is intra articular and a fracture of the medial condyle is likely.
Isolated fractures of the medial epicondyle are extraarticular and usually do not have positive fat pad signs.

In difficult cases an MRI or an arthogram may be helpful. Alternatively stress views under anaesthetic may be helpful in distinguishing between medial epicondylar fracture and medial condylar fracture.

Oblique views may help determining the true extent of displacement, as displacement of >2mm should be managed surgically to obtain an anatomical reduction of the articular surface.

Treatment

Type 1 - Minimally displaced fractures generally heal well with cast immobilization, with careful radiographic follow up.

Type 2 and 3 displaced fractures require anatomical reduction and rigid fixation to avoid non union, achieved with K wires or cancellous screws in adolescents nearing skeletal maturity.

Its important when performing an open reduction not to damage the trochlea's blood supply. Avoid the posterior surface of the trochlea and the medial aspect of the medial crista of the trochlea.

Place k-wires / fixation in metaphyseal part of the distal fragment if possible.

If not properly immobilized, whether by a cast or pin fixation, medial condylar fractures can go on to nonunion.

Complications

Avascular necrosis of the trochlea - blood supply to the trochlea is terminal, no collateral flow; blood supply enters posteriorly and can be disrupted by destruction of soft tissues during fracture or surgical attempts to reduce the fracture.
Nonunion - intra articular injury
Loss of reduction
Physeal injury - Salter Harris IV, viz Growth arrest
Ulnar nerve injury

Treatment of complications

Fowles and Ippolito et al. have suggested that the risk of avascular necrosis is high in the operative treatment of nonunion because takedown of the forearm flexors is required for exposure of the fracture site. Both authors reported better functional results from accepting a nonunion than acquiring avascular necrosis. Papavasiliou et al. suggested supracondylar osteotomy to improve motion and reduce deformity as an alternative to taking down the nonunion site in patients who present late.