PRP treatment refers to the injection treatment of platelet-rich plasma. How long PRP treatment for knee joint is effective depends on the degree of the lesion, and the results can be seen in 1~3 weeks after the treatment in general. PRP treatment for knee joint, mainly through the extraction of the body’s own venous blood, and then centrifugal purification, extraction of platelets, and then injected into the damaged joints, to repair the damaged tissues, used to repair the cartilage damage in the knee joint, such as osteoarthritis, meniscus damage, and so on. The prp treatment for knee joint is suitable for mild to moderate osteoarthritis, the pain can be reduced within 1 week after injection, if the joint degeneration is serious and the joint swelling is obvious, it may take 3 weeks to be effective. For knee arthritis with severe joint deformity it may not be effective and surgery is needed. For meniscus injury, 1 to 2 degrees of injury is generally quicker to see results and can be effective in about 2 weeks, if the meniscus is 3 degrees of injury, the effect may be slow or ineffective. Choosing prp treatment, patients should be under the guidance of the doctor according to the specific condition, a comprehensive assessment to determine the treatment program, if the treatment effect is not obvious, should be promptly replaced by other treatment methods.