Synovitis is the medical term for inflammation of the synovial membrane.This membrane lines joints which possess cavities, known as synovial joints. The condition is usually painful, particularly when the joint is moved. The joint usually swells due to synovial fluid collection. Synovitis may occur in association with arthritis as well as lupus, gout, and other conditions. Synovitis is more commonly found in rheumatoid arthritis than in other forms of arthritis, and can thus serve as a distinguishing factor, although it can present to a lesser degree in osteoarthritis. Long term occurrence of synovitis can result in degeneration of the joint.