Split peroneus brevis tendon: an unusual cause of ankle pain and instability.

Tears of the peroneus brevis tendon may cause ankle pain, swelling, and instability. Supportive therapy with ankle bracing and analgesics is the mainstay of therapy, but surgical repair is often required in patients with ongoing symptoms. Surgical options include debridement, tubularization, or, in severe cases, resection of the damaged tendon and tenodesis. We describe a 64-year-old woman with a split peroneus brevis tendon presenting with lateral ankle pain, swelling, and instability, and we review the literature regarding presentation, diagnostic testing, pathophysiology, predisposing factors, and treatment recommendations. Primary care physicians should consider peroneal tendon injuries in patients with chronic lateral ankle pain and instability.