Synovial chondromatosis is a disease affecting the synovium, a thin flexible membrane around a joint. Synovial chondromatosis is a disease affecting the synovium, a thin flexible membrane around a joint. People usually complain of pain in one joint, which persists for months, or even years, does not ease with exercise, steroid injection or heat treatment, shows nothing on X-ray, but shows a definite restriction of movement.