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.