Knee pain in middle-aged and elderly people mostly belongs to primary osteoarthritis, which is related to the aging of the joints themselves and overworked joints, but also closely related to the usual knee activities, poor blood circulation, cold and moisture, and obesity. The knee joint is the main weight-bearing joint of the human body. As the body grows older, the function of various organs gradually decreases, the mucus secretion in the joint cavity decreases, the articular cartilage dries out, gradually wears out and thins, and the joint bones become hypertrophic, coupled with the physiological atrophy of the muscles around the joint and the weakening of ligament elasticity, the mobility of the knee joint gradually decreases. With the development of the disease, there may gradually appear pain from movement, weight-bearing pain, pain without activity, pain at night, and pain at rest. The pain may be aggravated by excessive activity or changes in weather. The knee joint may become deformed, or the joint may become swollen due to joint effusion. X-rays may show narrowing of the joint space, unequal width or loss of the inner and outer space, formation of bone spurs at the edge of the intercondylar ridge and inferior patellar bone, and some intra-articular free bodies.