Destructive posttraumatic subtalar synovitis.

Destructive posttraumatic synovitis is a rare entity usually involving the knee. This case report details the evaluation and treatment of a rapidly progressive and destructive subtalar lesion that occurred in a healthy 27-year-old man after incidental trauma. Initial orthopedic evaluation revealed diffuse ankle tenderness and mild effusion. Radiographic and laboratory studies showed normal findings. Bone scan revealed significantly increased uptake in the talus. Subsequent computed tomography scan and magnetic resonance imaging studies showed a lateral soft-tissue mass invading both the talus and calcaneus with destruction of the subtalar joint. Tissue biopsy samples revealed hypertrophic synovium with villous projections, occasional giant cells, and occasional hemosiderin deposits. The lesion caused rapid and progressive destruction of the subtalar joint despite aggressive conservative measures. Ultimately, the patient underwent a subtalar arthrodesis that led to the resolution of his symptoms and resumption of work and recreational activities. While posttraumatic synovitis is a rarely encountered condition, the orthopedic surgeon must have an index of suspicion, perform a systematic evaluation, and render definitive treatment to ensure a successful outcome.