The human body is a complex machine, and a problem with one component can affect the normal functioning of the body. But the human body is different from an ordinary machine. Ordinary machines, if the parts are badly worn, or damaged, then directly replace a, can be new. Although the parts that make up the human body cannot be easily replaced, not all of the body’s “parts” are irreplaceable. Joint tissues, which are difficult to regenerate, can be replaced. What is a joint? The connection between bones is called a bone joint. There are two types of bone connections: direct and indirect, and joints are a form of indirect connection. In other words, a joint is a connection between two neighboring bones that is formed by a capsule of connective tissue with an underlying space and synovial fluid between the two bones. Whether or not a damaged joint can be repaired by the body itself depends on the location and extent of the damage. First, if it is an acute injury, that is, the joint suffered a fracture, the site of the damage is mainly for the bone (composed of bone tissue, can be regenerated) muscles and soft tissues, can go to the hospital through the reset bandage fixation, etc., to promote the healing of the fracture place, to get professional treatment, it can be healed. Second, if it is a chronic injury, such as osteoarthritis, it belongs to cartilage damage, (cartilage is not renewable). When the cartilage is worn out to a certain extent, it can be treated conservatively in mild cases, while arthroplasty is strongly recommended in severe cases. The synovial layer in the joint capsule produces synovial fluid, which provides nutrients and lubricates the joint. Therefore, the main supply of nutrients to the joints comes from the synovium, not from the blood circulation of the body. Compared with soft tissue injuries or non-joint fractures, the blood supply in the joints is poor, and then healing of joint injuries is relatively difficult. Human joints are lubricated and repaired by the secretion of synovial fluid, but this repair capacity is limited. Therefore, it is best to have a replacement for a damaged joint. Replacement of an artificial joint is simply cutting away a thin layer of the damaged joint surface and replacing it with a layer of joint surface, usually made of metal or polyethylene. This restores a normal quality of life. On the other hand, some patients with joint diseases may give up treatment due to concerns about joint replacement surgery, which may result in missing the best opportunity to return to a normal life. This may result in the best time to return to normal life, which will not only make future surgeries more difficult, but also significantly reduce the quality of life.