Ischemic necrosis of the femoral head is caused by the destruction and interruption of blood flow in the femoral head and the development of cystic changes in the femoral head, which leads to the collapse of the femoral head and the involvement of the cartilage of the hip joint surface, while osteoarthritis of the hip joint is caused by the lesion of the cartilage of the femoral head joint surface first and then the involvement of the internal femoral head, which leads to cystic changes in the femoral head. The treatment of both femoral head necrosis and hip osteoarthritis is the same in advanced stages, and both require joint replacement surgery. However, the diagnosis of these two diseases needs to be differentiated from each other in two aspects: First, from the aspect of medical history, femoral head necrosis is mostly seen in young adults, with a history of hormone use, heavy alcohol consumption or trauma, while hip osteoarthritis is mostly seen in elderly patients. Secondly, from the X-ray film, the early stage of femoral head necrosis is characterized by small or interrupted bone texture of the femoral head, uneven bone density, cystic and hardened femoral head, the joint gap is normal at this stage, and the femoral head becomes flat and collapsed at a later stage, and the joint gap can become narrower; the joint gap becomes narrower in the early stage of hip osteoarthritis, and the joint surface of the acetabulum and femoral head appears less smooth or wavy at the same time. The bone surface corresponding to the narrowing of the gap often has irregular osteosclerosis, and the head of the femur is mushroom-shaped. The osteophytes at the edge of the acetabulum form dense triangular bone masses or long curved strips that cover the outwardly enlarged head of the femur, and single or multiple cystic changes of varying sizes, slightly round, ovoid or irregular, can be seen under the bone surface of the weight-bearing area of the head of the femur and above the acetabulum. There is an essential difference between femoral head necrosis and hip osteoarthritis. The former is ischemic necrosis, which develops from the inside out, while osteoarthritis is mostly degenerative, which develops from the outside in.