Acetabular dysplasia is caused by the loss of concentric correspondence between the femoral head and the acetabulum, the mismatch between the head and the acetabulum, long-term mechanical wear and tear, resulting in degenerative changes of the femoral head and acetabular articular cartilage, subchondral sclerosis and cystic changes of the femoral head, hyperplasia of the acetabular rim, formation of bone redundancy, and narrowing of the joint space, etc. These are due to the lack of effective coverage of the femoral head by the acetabulum on the outside, increased stress per unit area, and stress These are all degenerative changes of the joint caused by the lack of effective coverage of the femoral head by the acetabulum, increased stress per unit area, and stress concentration in the weight-bearing area of the femoral head. Femoral head necrosis is caused by blood flow disorder of the femoral head, ischemia of the femoral head, and long-term insufficient blood supply, which causes osteoclasts to grow and erode the femoral head continuously, forming necrotic bone and causing bone collapse. Although both are joint space narrowing and both have wear and tear. However, the two are essentially different. Osteoarthrosis due to acetabular dysplasia is caused by congenital dysplasia and is not caused by ischemia of the femoral head, which has good subchondral blood flow. Femoral head necrosis, on the other hand, is caused by ischemia. Therefore, hip arthropathy secondary to acetabular dysplasia should not be treated as femoral head necrosis, as the two are completely different, and their pathology and X-ray manifestations are also different. Although artificial joint replacement is the only option for the advanced treatment of both diseases, there are differences in the surgical operation. Especially for early to mid-stage cases, the treatment methods are very different.