Unusual case of lateral subtalar joint dislocation associated with calcaneal fracture and lateral malleolus fracture.

INTRODUCTION

Subtalar dislocation is defined by a simultaneous total separation of the talocalcaneal and talonavicular joints. Lateral variety is the rarest. It is the result of a high energy trauma. It occurs following forced eversion, with the foot locked in a rut with pressure on the lateral aspect of the leg. Articular fractures of the calcaneus occur as a result of axial impact on the greater tuberosity.We report the case of a lateral subtalar dislocation associated with a calcaneal fracture.

CASE PRESENTATION: A 62-year-old man who presented to the emergency room following a 9 m fall. Initial examination revealed a swelling of the right foot and ankle with a deformity giving the appearance of a "flat foot" without skin opening. The neuro-vascular examination was normal.A radiological assessment including an antero-posterior and lateral X-ray of the right ankle and a axial view if the calcaneus, showed a calcaneal articular fracture and a lateral dislocation of the subtalar joint. CT scan confirmed the diagnosis. Closed reduction by external maneuvers failed. Through a lateral mini-approach centered on the subtalar joint, open reduction of the dislocation was achieved and controlled fluoroscopically. Osteosynthesis of the calcaneal fracture was performed using a percutaneous pinning. Consolidation was obtained at 3 months post-operatively.At the last follow-up, the patient reported occasional pain. The radiological assessment showed early arthritic changes of the subtalar joint.

CONCLUSION

In rare cases of subtalar dislocation, the direction of displacement, associated bone injuries, and open reduction would be responsible for a poor functional outcome. At present, there is no certain way to avoid subtalar osteoarthritis.