I guess I have a pretty unusual problem called extrasynovial synovial osteochrondromatosis. It's in my ankle. Can you tell me a little about what this is and what causes it?
Extrasynovial means the problem has to do with synovial fluid being outside of a joint. Synovium is the fluid that keeps the joints lubricated and moving smoothly. It is a viscous (slippery) membrane that lines the cartilage (cartilage covers the bone).
Normally, the synovial fluid stays inside the joint. Any synovial fluid outside the joint is considered extrasynovial. Now for osteochondromatosis: osteo refers to bone, chondro is the cartilage, and osis at the end of a word just tells us something is wrong. In this case, the synovium has started to proliferate or grow too much.
It clumps together with the cartilage forming small nodules that eventually harden. These tiny osteocartilaginous (bone and cartilage) bodies can stick to the synovium inside the joint. They can also move outside of the joint and become loose bodies floating around the various bones that form the ankle joint.
No one knows for sure why the synovium starts to overgrow. There is often a history of trauma or injury to the joint involved. But it can happen spontaneously, too. Sometimes the body breaks down and absorbs these tiny masses. In other cases, they get stuck between two bones or embedded in a tendon. The clinical picture is one of pain, loss of motion, and a joint that locks up with movement.
Brian Carpenter, DPM, FACFAS, and John Clyde, DPM. Extrasynovial Synovial Osteochondromatosis of the Ankle: A Case Report. In The Foot and Ankle Online Journal. June 2010. Vol. 3. No. 6.
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