The synovium is a thin layer of tissue only a few cells thick which lines the joints and tendon sheaths. The synovium acts to control the environment within the joint and tendon sheath. It does this in two ways: first, it acts as a membrane to determine what can pass into the joint space and what stays outside; second, the cells within the synovium produce substances that lubricate the joint.
The synovium inside joints can become irritated and thickened in conditions such as rheumatoid arthritis, this is called synovitis. The synovium in tendon sheaths can be inflamed in conditions such stenosing tenosynovitis of the wrist. Synovitis can be treated with medications, cortisone injections, and sometimes in must be removed, a procedure called a synovectomy.
Also Known As: Synovial Tissue