Bosworth fracture: Pathoanatomy, Complications, and Medium-term Results of Treatment.

Background: Bosworth fractures (BFs) with entrapment of a fibular fragment behind the posterior malleolus (PM) are rare but potentially serious injuries to the ankle. Despite an increased awareness through a more regular use of computed tomography (CT) scanning, there is still a scarcity of clinical outcome studies.

Methods: Over a course of 25 years, data on 23 patients treated for BF at our institutions (mean age 44 years) were collected prospectively. Of those, 16 patients had a Weber type B fracture with displacement of the proximal fibular fragment and 7 patients Weber type C fractures with displacement of the distal fibular fragment behind PM. All but 1 patient, who refused operative treatment, were treated with open reduction and internal fixation. A total of 21 patients were followed up for an average of 66 (range, 18-204) months.

Results: The PM was fractured in 96% and the Tillaux-Chaput tubercle in 13% of cases. In 80% of patients with preoperative CT scans, the fibular fragment was entrapped between the posterior aspect of the distal tibia and the displaced PM fragment. An initial attempt at closed reduction was successful in 4 of 7 Weber type C fractures and in none of 16 Weber type B fractures. The overall complication rate was 22%. Eighty-one percent of patients rated their results as good or excellent. The American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score at the final follow-up averaged 84.1 (range, 45-100). Risk factors for postoperative osteoarthritis and poor functional results included unsuccessful closed reduction, inadequate open reduction, and avascular necrosis of the talus. Clinical and radiographic results were correlated.

Conclusion: Unsuccessful initial reduction and failure to achieve anatomic open reduction were associated with posttraumatic arthritis whereas open anatomic reduction and internal fixation resulted in favorable functional and radiographic results in the medium to long term.