Synovial chondromatosis of the subtalar joint and tenosynovial chondromatosis of the posterior ankle.

Synovial chondromatosis is a rare, generally benign condition characterized by the formation of multiple cartilaginous nodules in the synovium of joints and occasionally on the tendon sheath or bursae. If the nodules are intra-articular, the condition is referred to as synovial chondromatosis; if extra-articular, tenosynovial chondromatosis. This space-occupying lesion can lead to chronic pain and limit the function of involved joints. We report a case of synovial chondromatosis involving the subtalar joint and tenosynovial chondromatosis involving the posterior ankle and review current definitions of this uncommon lower-extremity condition.