Synovial chondromatosis is a disease affecting the synovium, a thin flexible membrane around a joint.
Signs and symptoms
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. There are 3 defined stages to this disease:
early: no loose bodies but active synovial disease;
transitional: active synovial disease, and loose bodies;
late: loose bodies but no synovial disease;
In the early stages of the disease it is often confused with tendinitis and/or arthritis. Once it reaches transitional the loose bodies become apparent with X-ray in greater than 70% of cases, with MRI often showing where xray fails. In experienced hands, US is also useful for the diagnosis. In the disease, the thin flexible membrane of the synovium gradually forms blisters which calcify and enlarge. These nodules eventually break free and float around the joint space becoming larger – these add to the discomfort and stiffness of the joint. The disease is rare and little known and there is currently no known cure. The affected tissue will show up as a semi-solid mass in a MRI scan, final diagnosis is usually confirmed by taking a biopsy. Synovial chondromatosis occurs twice as commonly in males as females and usually in their forties. However, online communities for synovial chondromatosis patients have yielded a stark contrast, with equal representation from both genders and members diagnosed as young as late teenage/early 20s. The disease generally affects only one of the larger weight bearing joints – although the elbow, and wrist can also be affected. Rarely involves the temporal mandibular joint.
Cause
The exact underlying cause of synovial chondromatosis is unknown. Some evidence suggests trauma may play a role in its development as it mainly presents in weight-bearing joints. Infection has also been considered as a contributing factor. The condition is not inherited. Synovial chondromatosis can reportedly occur as either a primary or secondary form. Primary synovial chondromatosis, which is more rare, occurs spontaneously and does not appear to relate to any pre-existing conditions. Secondary synovial chondromatosis is the more common form and often occurs when there is pre-existent osteoarthritis, rheumatoid arthritis, osteonecrosis, osteochondritis dissecans, neuropathic osteoarthropathy, tuberculosis, or osteochondral fractures in the affected individual.
Diagnosis
Treatment
Treatment is frequently by means of removal of the loose bodies and of a partial or full synovectomy Full synovectomy is a moderately major operation and involves completely exposing the joint and removing the affected tissue. Partial synovectomy is normally done arthroscopically. Synovectomies are normally carried out by shaving the lining of the knee but there are other ways of achieving this by either freezing the synovium or by the use of radiation treatment. The need for further procedures is greater than 25% although normally the frequency of the required removal of loose bodies is reduced by the previous synovectomy. There have been documented cases of malignant transformation however this is rare. Whilst the condition can be described as a ‘benign growth’ it seldom affects more than one joint, and does not usually affect surrounding tissue.
