The knee joint is one of the major joints of the lower extremities, and osteoarthrosis of the knee joint is a common and frequent disease in the elderly. It is caused by wear and tear or degeneration of the articular cartilage, firstly, when walking up and down stairs or squatting, which means that the articular cartilage of the patellofemoral joint is worn out, and then it can develop into pain even when walking on a flat road, which means that the cartilage of the tibia and femur on the weight-bearing surface is worn out, resulting in unevenness of the joint surface, so that pain occurs when the local force increases. In the past, most people would think that an old man, rotundity, walking with a limp, nothing can be treated, the pain can only be relieved by taking some medicine, the root cause or can not be solved! That’s why we see so many elderly people walking around with crutches or pushing wheelchairs or carts, aiding their walking activities and swaying from side to side because the knee joint hurts so much. The advent of joint replacement surgery can completely solve the patient’s pain, can improve the function of the knee joint and improve the quality of life! As the name implies, a thin layer of worn cartilage and subchondral bone of the femur and tibia of the knee is shaved off, and a metal piece of cobalt-chromium-molybdenum alloy is fixed to the osteotomy surface with bone cement so that the femur and tibia are in contact with metal instead of bone, lined with a polyethylene pad that acts as a meniscus. This way the metal is not painful in contact with the polyethylene. By surface replacement, we mean that during the surgery we preserve the patient’s medial collateral ligament, the lateral collateral ligament, and in addition to the need to cut the anterior cruciate ligament, the anterior bundle of the posterior cruciate ligament is also cut, and some prostheses are required to preserve the posterior bundle of the posterior cruciate ligament, so it can be said that the vast majority of the structures of the knee joint are still preserved, so we say that this knee replacement surgery is a surface knee replacement surgery. From the 1960s, joint replacement surgery began to appear, and now joint replacement has become very mature, the operation time is 1.5 hours on average, after the operation the patient will have a significant reduction of pain, the mobility will be greatly improved, the force line of the limb will return to normal, the result is very sure!