Non-surgical treatment 1, avoiding weight-bearing: including partial weight-bearing and non-weight-bearing, only applied to pre-collapse femoral head necrosis, i.e. Ficat stage I and II. From the literature, the effect of the treatment method of avoiding weight-bearing alone is not ideal, and the success rate is less than 15%, while the application of this method can be considered for type A femoral head necrosis whose lesions are located on the medial side of the femoral head. 2, drug treatment: the application of drug treatment of femoral head necrosis is less reported, in short, the effect of drug treatment is not yet certain, but because of its non-invasive, is still an important research direction. 3, other treatment methods: such as electrical stimulation therapy, bloodletting therapy, hyperbaric oxygen therapy, etc., there are not many reports, the effect to be further determined. Second, surgical treatment 1, preservation of the femoral head surgery 1) central decompression: the theory of central decompression for ischemic necrosis of the femoral head is based on the theory of increased intraosseous pressure of osteonecrosis, through central decompression can reduce intraosseous pressure and increase blood flow in the femoral head, and central decompression can stimulate the growth of blood vessels in the decompression tunnel and promote the creeping replacement of necrotic bone . There are more articles about central decompression, and its efficacy is more controversial. Its efficacy is highly related to the stage of femoral head necrosis, but not much related to the etiology of femoral head necrosis. 2) Osteotomy: The purpose of osteotomy is to change the main weight-bearing zone of the femoral head, replacing the necrotic bone with normal bone as the main weight-bearing zone. This method includes trans-rotor rotational osteotomy, inter-rotor internal osteotomy and inter-rotor external osteotomy, etc. It can also be combined with bone grafting treatment, which is mainly suitable for patients with Ficat stage II and III and small lesions. 3) Osteotomy: Osteotomy includes autologous cancellous bone graft, autologous cortical bone graft, allogeneic bone graft and cartilage graft, which can be combined with other treatment methods such as central decompression, electrical stimulation and osteotomy. Among them, autologous cancellous bone and cortical bone graft are more frequently used. Autologous cancellous bone has good osteogenesis induction and can promote the repair of necrotic femoral head, while cortical bone plays a supporting role for articular cartilage and subchondral bone in the necrotic area during the repair of femoral head. Bone grafting methods include bone grafting after central decompression, slotting bone grafting at the craniocervical junction, opening a window in the articular cartilage of the femoral head, lifting cartilage bone grafting and then resetting the cartilage. Bone grafting can be used in patients with Ficat stage II, early stage III and patients who have failed central decompression. The recent efficacy of this method is more certain, but the long-term efficacy is still controversial. However, it is worthwhile to accelerate the repair of the femoral head with the help of bone graft and shorten the time of bed rest, and the combination of growth factors, electrical stimulation and other methods to promote bone healing can improve its efficacy. 4) Bone graft with blood supply: There are more methods of bone graft with blood supply, and the grafted bone can come from the iliac bone, greater trochanter or fibula, and it can be with myofibular or vascular tip, and the bone graft with blood supply can increase the blood supply to the femoral head and accelerate the bone healing compared with the common bone graft. The clinical results are reported in the literature, but the x-ray improvement is not satisfactory, and a significant proportion of patients still need arthroplasty in the long-term follow-up. 5) Medullary core decompression, trabecular metal AVN reconstruction rods (tantalum rods): trabecular metal AVN reconstruction rods are porous tantalum metal prostheses with porosity, three-dimensional structure and elastic modulus similar to cancellous bone, high coefficient of friction with bone helps maintain initial stability after implantation, can form structural support for the necrotic area after implantation, facilitates in vascularization of the osteonecrotic area, and can be used in a minimally invasive way implantation, all of these features are beneficial in preventing the collapse and repair of the necrotic area of the femoral head and delaying the age of the hip replacement. Tantalum rods are expensive, and the average 5-year clinical success rate is 87%. Although the success rate does not appear to be as high as that of total hip replacement, it is important to understand that tantalum rods have the highest relative success rate of all means of treating early AVN, are reliable, have no complications relative to other procedures, and can be performed in a minimally invasive manner. All these are incomparable to other surgical procedures. 2, joint replacement surgery 1) hip surface replacement: hip surface replacement is to replace the joint surface with an implant, preserving the acetabulum and most of the subchondral bone of the femoral head, without invading the femoral neck and femoral bone marrow cavity, to complete the treatment of the disease while preserving as much as possible the normal physiological anatomical structure and relationship. First of all, because of the preservation of part of the femoral head and femoral neck, it provides a variety of options for remedy after surgical failure, such as arthrofusion, pseudoarthroplasty, re-surface replacement, conventional femoral prosthesis replacement matched with the original acetabular prosthesis, and conventional total hip replacement. When a revision is performed with a conventional femoral prosthesis with a stem, the treatment of the femoral medullary cavity and the difficulty of prosthesis installation are close to those of the initial surgery. Secondly, the surface replacement surgery basically maintains the original anatomical form and relationship of the joint, which makes the stress distribution and force transmission more in line with the normal biomechanical pattern and effectively reduces the stress masking of the proximal femoral segment that occurs after traditional total hip replacement. Third, since the bone marrow cavity is not opened, the possibility of infection is theoretically reduced, and there are no other intramedullary complications caused by the femoral prosthesis with stem. However, the above theoretical advantages cannot always be reflected in clinical practice and need to be further studied in depth. 2) Total hip arthroplasty: It is the only option for the treatment of advanced femoral head necrosis. With the progress of friction interface research and the application of new materials (such as ceramic artificial joints), there is a tendency for the population with indications for total hip arthroplasty to be younger.