An unusual injury: A case of open and irreducible lateral subtalar dislocation

Abstract text (incl. references and figure legends)

Case history

A 36-year-old male arrived at the emergency service due to a high-energy accident involving his left ankle

Clinical findings

An open lateral subtalar dislocation was observed, with no palpable pedal pulse. Posterior tibial pulse and neurological status were conserved.

Investigation/Results

Antibiotherapy was administered. X-rays showed a lateral subtalar dislocation with no apparent fractures. The patient was admitted for urgent intervention

Diagnosis

Gustilo IIIA open lateral subtalar dislocation

Therapy and Progressions

During the intervention, flexor digitorum communis laceration, and an irreducible dislocation due to interposition of the posterior tibialis tendon were found. Reduction was achieved by applying traction, valgus, and mobilization of the tendon. An external fixator was placed. Pedal pulse was recovered.

The external fixator was removed at 3 weeks, and MRI was performed, showing fractures of the external tuberosity and talar dome. Flattening of the longitudinal arch was observed.

At 5 months, the patient presents complete range of motion and assisted weight-bearing.

Comments

Subtalar dislocations are high-energy unusual injuries. Regarding lateral dislocations, 70% present neurovascular injuries and up to 80% of open dislocations are lateral.

In irreducible cases (0-47%) open reduction must be performed to movilize the interposed structures (bone fragment, posterior tibialis tendon or flexor hallucis longus in lateral dislocations). After the reduction of open dislocations, placing an external fixator is recommended. CT or MRI must be performed to identify associated lesions, such as talus fractures and others. Their presence is related to a worse prognosis. Immobilization period should be as short as possible.

References

Prada-Cañizares A, Auñón-Martín I, Vilá Y Rico J, Pretell-Mazzini J . Subtalar dislocation: management and prognosis for an uncommon orthopaedic condition. Int Orthop. 2016 May;40(5):999-1007

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