Rare Bosworth Fracture-Dislocation Variant of an Irreducible Distal Fibula Dislocation of the Ankle Without Fibula Fracture

BACKGROUND: Irreducible fracture-dislocations of the ankle are rare orthopedic emergencies that should not be missed. The Bosworth fracture-dislocation is a rare fracture where an incarcerated fibula fragment remains locked behind the posterior lateral tubercle of the tibia. We present a case describing a variation of a Bosworth injury, with a dislocation of an intact distal fibula with an associated medial malleolus fracture. METHODS: Our patient is a 55-year old male who presented to the emergency department with a left ankle injury after being involved in a road traffic accident. Radiographs show a posterior dislocation of an intact distal fibula associated with a fracture of the medial malleolus and disruption of the ankle mortise. RESULTS: An attempt to reduce the dislocation at the emergency department under sedation was unsuccessful. The patient was subsequently taken to the operating theatre for manipulation and reduction and application of an external fixator. Definitive fixation was performed successfully a week later. CONCLUSION: A high index of suspicion is critical for diagnosing a Bosworth fracture-dislocation, as this diagnosis is commonly missed. Early diagnosis and proper surgical anatomic reduction are important to prevent chronic ankle instability and evolution towards ankle arthritis. LEVEL OF EVIDENCE: Level IV, case study.