Osteoarthrosis (OA), also known as proliferative arthritis, degenerative arthritis, age-related arthritis, and hypertrophic arthritis of the knee, is a common knee disorder in the elderly. It is a chronic inflammatory disease of the knee caused by degenerative changes of the knee cartilage, mainly osteophytes at the edge of the joint, involving cartilage and subchondral bone, synovium, joint capsule and other important structures of the joint. Pathologically, the disease is characterized by lacunar and focal erosive cartilage damage, cartilage loss and structural destruction, subchondral osteosclerosis, bone cysts, and joint marginal bone redundancy formation. Clinically, it mainly manifests as knee pain and varying degrees of dysfunction, partly with joint swelling and effusion, which seriously affects the quality of life of patients. I. Etiology The etiology of primary OA is not fully understood, it is generally believed that the following factors: 1, age: from middle age to old age, with the growth of age, often degenerative changes in articular cartilage, joint strain over the years is an important factor. 2, gender: both men and women can be affected, but more common in women, especially women before and after menopause. This indicates that the disease may be related to hormonal changes in the body. 3, weight factors: the incidence is higher in people with obesity and thick body type. Felson reported that weight loss of only 5 kg in 10 years can reduce the risk factors of knee OA by 50％. 4, joint injury and overuse: any cause of abnormal joint shape can change the transmission of joint load, the local load on the articular cartilage surface and increased wear and tear, can cause OA. 5, bone density: when the subchondral bone trabeculae become thin and hard, its ability to withstand the pressure decreases. Therefore, the chances of OA are higher in people with osteoporosis. 6, other factors: with genetic mutations, immunological abnormalities and other factors may be related. Second, the diagnosis is generally based on the patient’s symptoms, signs and imaging manifestations. The symptoms include pain, stiffness, impaired movement, joint instability, etc. The signs include reduced range of motion, joint effusion, bony swelling, movement popping, deformity, etc. The imaging manifestations include joint space narrowing, bone formation, subchondral plate sclerosis, cystic changes, etc. X-ray examination is still the basis for the diagnosis, classification and staging of osteoarthritis. In 1995, the American Rheumatism Association established the following diagnostic criteria for osteoarthritis of the knee: Clinical criteria: 1. recurrent knee pain in the past month; 2. bone rubbing sounds during joint movement; 3. morning stiffness.