Joint swelling and pain may be caused by over-exercise or trauma, degenerative knee disease, autoimmune and other reasons. 1. Excessive exercise or trauma: Excessive exercise will cause an increase in the metabolism of the muscles around the knee joint, an increase in the exudation of joint fluid and congestion of the blood vessels, resulting in joint swelling and pain; trauma is a direct violence injury, which can directly cause damage to the bones and soft tissues of the knee joint, and joint swelling and pain will occur. For example, patella fracture, meniscus tear. 2. Knee degenerative disease: mainly due to ageing, long-term wear and tear of the joints, osteomalacia, osteophyte formation, synovial membrane hyperplasia, cartilage degeneration, resulting in joint pain, swelling and restricted activities. 3. Autoimmunity: mainly due to various rheumatism, rheumatoid factor and knee joint synovial membrane, joint lubricating fluid structure is similar, resulting in autoimmune reaction, synovial membrane hyperplasia, articular cartilage damage, resulting in joint swelling and pain. Rheumatoid knee osteoarthritis, rheumatoid knee osteoarthritis, gouty knee osteoarthritis and so on. Joint swelling and pain alone can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results to make an accurate judgment, it is recommended to go to the hospital in a timely manner to consult the doctor to clarify the cause of the disease.