Synovial hyperplasia is often caused by several factors: First, it may be caused by cold in the area. In the joints of the body, the soft tissue cover is relatively thin, and at the ends of the limbs, patients may be underdressed, making it very easy to get cold in these areas. Once this area is cold, the synovial membrane inside the joint may become enlarged, causing pain in the joint. In addition, it may lead to an increase in synovial fluid secretion, and then the joint space is very full. Second, due to traumatic factors. For example, contusions, fractures, dislocations, and other injuries to the joints may stimulate the synovial membrane and result in hyperplasia during the recovery process. Third, due to the body’s internal immune response. For example, when rheumatoid or rheumatoid arthritis strikes, it is possible that the wrong immune response will attack the synovium. This can also cause abnormal synovial hyperplasia. Fourth, it may be caused by overuse of the joints. For example, excessive wear and tear in the joints caused by overuse of the joints may also lead to synovial hyperplasia.