Introduction
Synovitis or synovitis is an inflammation of the inner layer of the joint capsule, the membrana synovialis. This membrane, also known as the synovial membrane, lines the inner surfaces of all joint capsules, tendon sheaths and synovial bursae. It is responsible for the production of synovial fluid (synovia), which not only serves to absorb shocks to the joint, but also contains glucose to feed the avascular joint cartilage.
An intact synovial membrane is essential for a healthy, functional joint. Inflammation of the synovial membrane is divided into two forms; acute and chronic synovitis. They sometimes differ greatly in their course and prognosis and therefore also in the approach to their treatment. Particularly in chronic synovitis, a coral-like growth of the membrane occurs, resulting in the destruction of joint cartilage, ligaments and tendons. The destruction of bony structures is also possible.
Causes
Synovitis is a major problem, especially in the context of a number of basic joint diseases. Older people are often affected by synovialitis, which occurs as a result of chronic wear and tear of the joint surfaces. Likewise, inflammatory processes of the synovialis occur particularly in the context of rheumatoid arthritis, juvenile arthritis and psoriatic arthritis (psoariasis-arthritis).
Since inflammatory processes also take place in the joints in the course of lupus erythematosus (butterfly lichen), these patients often suffer from joint capsule inflammation. On the other hand, occupational groups that are predominantly active in a kneeling position are often affected by synovilaitis of the knee. Tilers and cleaning staff are typical examples of occupational synovitis.
Likewise, athletes with a chronic strain on the musculoskeletal system without adequate periods of relief or incompletely healed joint injuries can also become ill. The mechanism of origin is similar in all these patient groups: Especially at the transition from joint surface to joint capsule, progressive inflammatory processes occur, which cause cell division and growth of the epithelial cells of the synovialis. During the course of the disease, the immigration of inflammatory cells leads to a cauliflower-like proliferation of the epithelial cells into the joint space and surrounding tissue, thereby causing destruction of cartilage and bone tissue as well as adjacent ligaments, tendons and other tissues.
Knee TEP is an extremely invasive procedure in which the joint capsule is completely opened and all joint surfaces are then replaced with prosthetic material. Parts of the joint capsule and the synovial membrane are removed, as they have no essential function for the artificial joint. At the end of the operation, the capsule is sutured and left in its anatomically correct position.
In the further course of the operation, the prosthesis structure may cause so-called “abrasion synovitis” on parts of the remaining synovial membrane. The inflamed synovial membrane can cause pain and lead to effusions and swelling of the joint. If the synovitis occurs over a longer period of time, it may be necessary to repeat the operation to remove the joint mucosa.
