Posterior knee effusion is generally referred to as knee joint effusion and should be treated according to the cause of the joint effusion. Common causes include osteoarthritis, rheumatoid arthritis, gouty arthritis and so on. Commonly used treatments include general treatment, physical therapy, medication and surgery. 1. Osteoarthritis: appropriate rest, reduce the activity of the diseased joints; massage, acupuncture, etc. to promote local blood circulation, reduce the inflammatory reaction; commonly used non-steroidal analgesic anti-inflammatory drugs such as ibuprofen, aspirin, etc. to reduce joint pain, control inflammation; can be injected into the joint cavity glucocorticosteroids such as budesonide, dexamethasone, etc.; joint puncture to extract fluid in case of more fluid accumulation. 2. Rheumatoid arthritis: in addition to the above treatments, we should actively treat the primary disease. Commonly used drugs include salazosulfapyridine and methotrexate. If the joint function is seriously affected, surgery can be performed. 3. Gouty arthritis: control the primary disease, symptomatic treatment, in addition to the above symptomatic treatment, should also change the lifestyle, avoid drinking alcohol, wet and cold environment. Colchicine, allopurinol and other drugs can quickly control the inflammatory reaction and relieve pain. Surgery can be considered if accompanied by gout stones that keep getting bigger. There may be other causes of joint effusion, such as trauma, etc. It is recommended to improve the examination in time, clarify the cause of the disease, and standardize the treatment under the guidance of the doctor. The above drugs should be used reasonably under the guidance of a doctor, avoid self-medication.