Fracture of the os peroneum with rupture of the peroneus longus tendon. A case report and review of the literature.

Subcutaneous rupture of the peroneus longus tendon occurring through a fracture of the os peroneum sesamoid in the foot, confirmed at surgery, is a rare injury, possibly with only one previously reported case. In the present case, the patient fell from a curb with the foot and ankle in supination; to prevent the fall, the patient forcibly everted the foot and ankle. Differential diagnosis of the injury includes chronic ankle ligament sprains, avulsion of the bony insertion of the peroneus brevis tendon, peroneal tendon subluxation, trauma to a congenitally multipartite os peroneum, and calcific tendonitis of the peroneus longus tendon. Primary repair with surgical approximation of the fractured os peroneum was performed with a satisfactory outcome.