Femoral head necrosis is a common clinical disease, according to the United States statistics, the annual new cases in 15,000 to 20,000, involving cases in 300,000 to 600,000, as a projection, China’s annual new cases of more than 200,000, the accumulated cases are more considerable. Most of these patients are young and middle-aged, and about 55-60% of them are involved in both hips. The disease has a high disability rate, and studies of its natural course show that without effective treatment, about 80% of femoral head necrosis will result in femoral head collapse 1 to 3 years after the onset of the disease, eventually causing severe osteoarthritis and serious joint dysfunction. Femoral head necrosis is not an incurable disease, and different treatment methods can be used at different times of the disease to preserve the function of the hip joint as much as possible, allowing patients to return to work and gain a normal social life. The pathophysiological change of osteonecrosis is a process of bone necrosis and repair, which results in the formation of a sclerotic zone between normal bone tissue and necrotic bone, making it impossible for vascular tissue to grow in, and the necrotic bone loses its normal structure as well as its biomechanical support properties. In femoral head necrosis, the subchondral bone plate is broken and the femoral head collapses, resulting in serious osteoarthritis of the hip joint and causing dysfunction of the hip joint. However, not all cases of femoral head necrosis will progress to femoral head collapse. Minimally invasive surgical methods to preserve the femoral head are used to remove the necrotic tissue from the femoral head and implant autologous bone and artificial osteogenic material, while adding autologous bone marrow stem cells to promote bone growth and achieve the biomechanical support of normal bone tissue to prevent femoral head collapse from occurring. Preserving the femoral head or delaying the hip replacement as much as possible. Early and accurate diagnosis and scientific staging is the key to successful joint preservation treatment. Femoral head necrosis can be caused by both trauma (femoral neck fracture, hip dislocation, etc.) and non-traumatic causes. In China, non-traumatic osteonecrosis is mainly caused by glucocorticoids and alcoholism. It is often difficult to obtain early diagnosis, mainly because most of the cases are asymptomatic or lightly symptomatic in early stage, so patients do not consult the doctor in time or the doctor is not alert to this disease, and most of the cases are only X-ray or CT scan examination and the osteonecrosis of femoral head is not shown in stage I. Even if it has progressed to stage II, some lesions are still not shown. To achieve early diagnosis of non-traumatic femoral head necrosis, MRI should be used for high-risk patients as early as possible. Patients who can be classified as high risk for non-traumatic femoral head necrosis include those who use high doses of corticosteroids (more than 2000 mg) or shock therapy for a short period of time, chronic heavy alcohol abuse, patients with a history of trauma to the hip who are highly coagulated and those who work in decompression environments such as underwater. Studies have shown that osteonecrosis occurs in some patients with high doses of hormones, which can be shown on MRI as early as 2 weeks after drug administration and mostly within 3 months. Currently, there is a tendency to expand the diagnosis of femoral head necrosis in China. In addition to commercial interests, the lack of understanding of the pathological changes of typical femoral head necrosis is one of the reasons for this tendency. It should be clearly understood that the bone and bone marrow are firstly involved in femoral head necrosis, therefore, the articular cartilage does not change in the early and middle stages, even if the femoral head starts to collapse, the joint space can still be largely preserved. The joint space has narrowed or disappeared in the early and middle stages. CT scans can show the lesions more clearly, especially the Crescent sign in stage III, which indicates a subchondral fracture. Scientific staging is a guide for choosing the right treatment and determining the prognosis. Currently, the accepted staging methods are ARCO staging and Steinberg staging by Penn State University. Both are basically similar. Stage 0 means all non-invasive examinations are negative, stage I is negative for X-ray and CT, while bone scan and MRI are positive. Stage II is the presence of osteonecrotic lesions on X-ray and CT with an intact subchondral bone plate.