Primary synovial chondromatosis of the subtalar joint presenting as ankle instability

摘要

Synovial chondromatosis is a benign synovial tumor, most commonly involving large joints such as the shoulder, elbow, hip, and knee. A higher prevalence has been found in males. Occurrence in the foot and ankle is uncommon, although there have been previous reports in the orthopedic and radiological literature of primary synovial chondromatosis in the calcaneocuboid, tibiotalar, naviculocuneiform, metatarsophalangeal joints, tarsal tunnel tenosynovium, and retrocalcaneal bursa. Occurrence in the subta-lar joint is even more rare, with only a few reports in the literature to date, and each with follow-up of 2 years or less.