Knee effusion, i.e. knee joint effusion, the main symptoms are swelling of the knee joint, obvious pain, restricted movement and limp. 1. Knee joint swelling: after knee joint effusion because of the presence of fluid in the joint, usually the fluid is retained in the suprapatellar bursa, there will be swelling of the knee joint, and the affected side and the healthy side will be clearly seen when comparing the affected side of the knee joint is full and swollen. Positive floating patella test. 2. Obvious pain: because of the fluid in the knee joint, the pressure in the knee joint increases, which irritates the synovial membrane and causes pain in the knee joint. In addition, the synovial membrane also secretes inflammatory factors, which can also lead to symptoms of knee joint pain. After the accumulation of fluid in the knee joint, there will be pressure and pain points, and sometimes the local skin temperature increases. 3. Restricted activities and limp: patients because of the fluid in the knee joint joint joint swelling and pain, walking will appear limp and limited activities. Difficulty in moving and squatting. Long-term, excessive, strenuous exercise or activity is one of the causes of joint effusion, so patients with knee joint effusion need to avoid strenuous exercise, timely treatment of joint injuries, and also need to lose weight to reduce the burden on the knee.