The etiology of femoral head necrosis is diverse (about 60 kinds), complex and difficult to classify in a comprehensive and systematic way, which is related to the unclear pathogenesis. We have summarized more than ten common pathogenic factors in the long-term theoretical research and clinical treatment as follows: 1. Trauma causes femoral head necrosis. Such as external impact caused by femoral neck fracture, hip dislocation, hip joint sprain and contusion. Trauma is the main factor causing femoral head necrosis. However, the occurrence and extent of ischemic necrosis of the femoral head due to trauma mainly depends on the degree of vascular destruction and the compensatory capacity of the collateral circulation. 2, drugs lead to femoral head necrosis. Such as long-term use of hormonal drugs due to bronchitis, asthma, rheumatism, rheumatoid, neck, shoulder, back and leg pain, diabetes, skin disorders, etc.. It is an early statement that the accumulation of hormones in the organism due to the large amount or long-term use of hormones has led to the development of the disease. Recently, it is believed that the occurrence of femoral head necrosis is directly related to the type, dosage form and route of administration of hormones, and is not directly proportional to the total amount and duration of hormones. However, the long-term use of large amounts of hormones or excessive daily doses, dose increases and decreases suddenly is also one of the reasons for the occurrence of necrosis of the femoral head. 3, alcohol stimulation leads to femoral head necrosis. The accumulation of alcohol in the body due to long-term heavy drinking leads to the increase of blood lipids and damage to liver function. Elevated blood lipids, resulting in increased blood viscosity, blood flow slows down, so that blood coagulation changes, and therefore can make the blood vessels blocked, bleeding or fat embolism, resulting in osteonecrosis. Clinical manifestations are aggravated by alcohol, walking duck walk, heart failure, weakness, abdominal pain, nausea and vomiting, etc. 4, wind, cold, wet lead to femoral head necrosis. Clinical manifestations are hip pain, cold and damp, squatting difficulties. 5, liver and kidney deficiency leads to femoral head necrosis. The manifestations are general wasting, yellow face, impotence, premature ejaculation, dreaming, spermatorrhea, weakness, etc. 6, osteonecrosis due to osteoporosis. Clinical manifestations are weakness of lower limbs, pain, inability to bear weight and easy to fracture. 7, flat hip leads to osteonecrosis. Clinical manifestations are walking duck step, short lower limbs, muscle atrophy, about 50 meters of pain gradually aggravated, functional limitations, etc. 8, abnormal bone marrow hyperplasia leads to osteonecrosis. The performance of the affected limb cold, sore, can not bear weight, easy to fracture, bone atrophy, etc. 9.Bone tuberculosis combined with osteonecrosis. The manifestation is positive nodule test, low fever in the afternoon, pain with a fixed place, wasting, night sweats, weakness, etc. 10, post-surgical osteonecrosis. In the clinical bone graft, vascular graft three years later, osteonecrosis occurs due to insufficient blood supply to the bone. In addition, there are pneumatic, radiological and hematological diseases. Among the above many factors, osteonecrosis of the femoral head caused by local trauma, abuse of hormonal drugs, and excessive alcohol consumption is common. The common core problem is the impaired blood circulation of the femoral head caused by various reasons, which leads to ischemia, degeneration and necrosis of bone cells. So how does trauma lead to femoral head necrosis? The cause of femoral head necrosis due to trauma is due to damage to the blood vessels supplying the femoral head, such as damage to the lateral epiphyseal vessels. When these vessels are damaged, the femoral head loses all or part of its blood flow, which can cause ischemic necrosis after 8 hours of post-injury blood flow blockage. Thus, in displaced femoral neck fractures, osteonecrosis can occur very early. Ischemic necrosis of the femoral head accounts for 85% of displaced femoral neck fractures and 15%-25% of nondisplaced fractures. Ischemic necrosis of the femoral head has also been reported after penetration of the needle in intertrochanteric fractures, due to the possibility of injury to the lateral epiphyseal vessels (the needle enters the femoral head from above or behind the lateral aspect of the femoral head) during the penetration of the needle. Injury to this vessel can cause local ischemic necrosis of the femoral head and eventually collapse in the upper weight-bearing part of the femoral head.