1.Why do we need to replace the joint? A: Because it can eliminate joint pain and restore joint function at the same time. 2. What kind of diseases need to replace the hip joint? A: Hip joint lesions causing hip pain and dysfunction, can not be applied to other treatments and can only use head and neck resection or joint fusion of patients, is the main indication for total hip replacement. Specific indications are: 1) Femoral neck fracture Aged femoral neck fracture, head and socket have been destroyed and painful and affect the function. fresh intra-articular femoral neck fracture around 60 years old, should try to ensure early activity to avoid the series of complications of long-term bed rest, such as: lung infection, urinary tract infection, bedsores and so on. Especially the elderly femoral neck fracture patients. (2) Ischemic necrosis of the femoral head, including traumatic, idiopathic, cortisone or ethanol poisoning caused by ischemic necrosis of the femoral head. For ischemic necrosis of the femoral head stage 1 and 2, the femoral head, acetabular shape is complete, the joint space is normal or slightly narrowed, and the pain can not be relieved by conservative treatment, it is feasible to drill and decompression of the head and neck, and rotational osteotomy in the rough area of the augmentation area and other surgeries in order to improve the symptoms, but the patients who have enough money can also consider the high life expectancy prosthesis and artificial joint replacement. (2) Degenerative osteoarthritis Mostly seen in the elderly, for severe pain osteoarthritis, there are more serious pain and dysfunction, the feasibility of total hip arthroplasty. (4) Rheumatoid arthritis and ankylosing spondylitis Mostly younger patients with hip pain or severe limitation of activities due to ankylosis, the patient’s study, work and marital problems are affected. For this type of patients. Especially for those with bilateral hip and spine involvement, the age limit should be relaxed and total hip replacement should be performed earlier. After surgery, even if you get limited joint activity that, will make the patient feel much more convenient. 5) Hip ankylosis Hip pain is the most important indication for surgery. Unilateral hip joint physiological position ankylosis without pain, not complete osteoarthritis of the hip joint, and pain and deformity feasible replacement surgery. Complete osteoarthritis of the hip joint, due to hip deformity can cause degenerative osteoarthritis of the neighboring joints, and cause pain and instability. (6) Chronic hip dislocation mainly includes congenital hip dislocation, hip f3 dysplasia, as well as due to trauma and infection leading to 7,17-dimethyltestoscerone old dislocation and gradually aggravate the obvious pain. 7) Bone tumors Low-grade malignant tumors located in the neck of the femoral head or acetabulum, such as giant cell tumor, chondrosarcoma, etc., can be considered for artificial total joint replacement. 3.What diseases need knee replacement? 1) It is applicable to advanced knee joint lesions other than infection and severe neurogenic arthritis. The period of pain and dysfunction of the patient’s affected knee should be longer than one year. Total knee replacement can only be considered when various conservative treatments have failed for at least six months and X-rays show advanced lesions (joint space changes). Including: rheumatoid arthritis, osteoarthritis, hemophilic arthritis, traumatic arthritis, Charcot’s arthritis, etc.; 2) infectious arthritis with residual dysfunction, and the infection is under control; 3) benign tumors around the knee joint; 4) a few primary or secondary osteochondral necrosis disorders.