Synovitis is a series of symptoms caused by physical, biological, chemical and immunologic factors that stimulate the synovial membrane, resulting in synovial hyperplasia and increased synovial fluid secretion. Rheumatoid arthritis is a type of arthritis, and the main cause of the disease is an allergic reaction disease of the rheumatic immune system. Synovitis mainly affects the synovial membrane, but less so the bone and articular cartilage. Rheumatoid arthritis, however, does not only attack the synovial membrane, but also the articular cartilage and bone in the joints, ultimately resulting in the loss of joint function.