Having fluid in the knee joint does not necessarily mean synovitis. Synovitis can cause a small amount of fluid in the knee joint. However, meniscal injury, ligament injury or fracture, bone contusion, rheumatoid arthritis, rheumatoid arthritis and other underlying diseases can cause knee effusion, and it can even be understood that knee effusion is accompanied by other diseases and is not a complete diagnosis of the disease. In addition, physical therapy should be used to promote the development of the knee joint. In addition, physical therapy is used to promote the gradual absorption of joint effusion, and the whole process is time-consuming. If you have enough patience, because as long as the knee joint moves, a small amount of knee joint fluid is produced inside, and the absorption and production do not reach a balanced state, a small amount of joint fluid is difficult to disappear.