For the elderly, the main diseases that cause hip pain and dysfunction are the following: 1, hip osteoarthritis: hip osteoarthritis causes joint deformity and destruction is the most common disease of artificial hip replacement, mainly including primary osteoarthritis and secondary osteoarthritis. Primary osteoarthritis is mainly caused by the degeneration of the cartilage itself, while other factors, such as congenital hip dysplasia, hip fracture dislocation and other causes of joint destruction are called secondary osteoarthritis. The main clinical manifestations are hip joint pain, functional limitation, narrowing of the hip joint space, osteophytes around the joint, and even hip joint deformation and destruction in X-ray films. 2.Femoral neck fracture: In terms of fresh fracture alone, closed reduction internal fixation treatment is generally preferred, and artificial hip replacement is not the preferred treatment for femoral neck fracture. However, for elderly people, especially those who are over 65 years old, with obvious fracture displacement or comminution, systemic diseases and less than ideal bone condition, it is very suitable to perform artificial hip replacement. This is because for such elderly people, they can move around early after the artificial hip replacement, which greatly reduces the complications caused by long-term bed rest and the pain caused by femoral head necrosis after internal fixation. At the same time, the artificial total hip replacement is also suitable for femoral neck fracture secondary to non-union of femoral neck fracture and femoral head necrosis. 3, femoral head necrosis: also known as aseptic necrosis or ischemic necrosis of the femoral head, the exact cause of the disease is not very clear, it is generally believed that there are traumatic causes such as femoral neck fracture and hip dislocation, non-traumatic causes such as the systemic application of high doses of corticosteroids and excessive alcohol intake, recently some scholars also believe that the genetic mutation caused by local microcirculatory disorders of the femoral head caused by femoral head necrosis. Recently, it has also been suggested that the femoral head necrosis is caused by local microcirculatory disorders in the femoral head due to genetic mutations. At present, the treatment of this disease is mainly based on different treatment methods according to the severity of the lesion. Artificial hip joint replacement is mainly for patients whose femoral head has been deformed and collapsed, and whose hip joint gap has been narrowed and osteophytes have grown. 4, local hip lesions caused by systemic diseases: the most common systemic diseases that cause hip lesions are rheumatoid arthritis and ankylosing spondylitis. In the early and middle stages of the disease, we generally use internal medicine, but in the late stage, especially when the hip joint space is found to narrow and disappear, the hip joint is very painful and cannot be relieved by medicine, then hip joint replacement must be performed. However, special attention should be paid to the fact that the surgery should not be performed during the active period of the disease, that is, when the blood sedimentation is very high, because if the surgery is performed during the active period of the disease, the risk of the surgery will be very high and it is easy to have systemic complications causing accidents. 5.Bone tumor involving the joint or near the joint: the use of artificial joint replacement is one of the important means to preserve the function of the joint, but generally requires a customized prosthesis to meet the needs of different individuals. Infectious disease: Infection was previously considered a contraindication to surgery, but in recent years it is believed that artificial hip arthroplasty can be performed in cases where the infection has been controlled, and the number of successfully treated cases reported in the literature is increasing year by year. However, patients with active local or other infections are not suitable for arthroplasty.