Split Peroneus Brevis: An Overlooked Cause of Ankle Dysfunction

Introduction: Split tears of the peroneus brevis tendon (PBT), often associated with superior peroneal retinaculum (SPR) insufficiency, are a frequently overlooked cause of posterolateral ankle pain and instability, particularly in athletes. Accurate diagnosis requires a high index of suspicion and dynamic imaging to detect tendon subluxation and associated pathology. Case Report: We present the case of a 28-year-old athlete with persistent posterolateral ankle pain and instability following an ankle twist. Clinical examination and imaging confirmed a partial longitudinal tear of the PBT with concomitant SPR insufficiency. Surgical management involved tendon debridement, tubularization with side-to-side repair, and SPR reconstruction. Post-operative rehabilitation included progressive weight-bearing, range-of-motion exercises, and structured strengthening protocols. Conclusion: The patient achieved excellent recovery, with an American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Score of 85 at 3 months and a full return to sports without pain or instability. This case highlights the importance of early recognition and comprehensive management of both tendon and ligament pathology to achieve optimal functional outcomes.