Synovitis is the inflammation of a synovial (joint-lining) membrane, usually painful, particularly on motion, and characterized by swelling, due to effusion (fluid collection) in a synovial sac.
Synovial fluid is a transparent, viscid fluid secreted by the synovial membrane and found in joint cavities, bursae, and tendon sheaths. Analysis of synovial fluid aspirated from a joint can confirm or rule out various joint diseases such as traumatic arthritis, osteoarthritis, gout, and rheumatoid arthritis.
Synovitis is a major problem in rheumatoid arthritis, in juvenile arthritis, in lupus, and in psoriatic arthritis. It may also be associated with rheumatic fever,tuberculosis, trauma, or gout.
Rheumatoid arthritis involves synovitis. In rheumatoid arthritis, the synovial membrane lining the joint becomes inflamed. The cells in the membrane divide and grow and inflammatory cells come into the joint from other parts of the body.