Osteonecrosis of the femoral head (ONFH), also known as ischemic necrosis of the femoral head (Avascular Necrosis), is a common and difficult to treat disease in the field of orthopedics.ONFH is a disease in which the blood supply to the femoral head is interrupted or impaired, causing the death and subsequent repair of bone cells and bone marrow components, which subsequently leads to structural changes in the femoral head, collapse of the femoral head, and joint dysfunction. Why is the femoral head prone to necrosis? 1.Big Load: The hip joint is the largest joint in the human body, and the maximum load can reach 5.8 times of body weight when walking. 2, Shear Load: The femoral head has a neck stem angle and anterior tilt angle, gravity from the acetabulum through the femoral head, neck migration to the femoral stem, the line of force is not vertical, the formation of shear force. The shear force causes the blood supply to the bone to be affected. 3.Big Movement Range: The range of movement is second only to the shoulder joint, and there are more chances of injury. 4.Low blood supply (Poor Blood Supply): Insufficient blood supply is one of the most important causes of femoral head necrosis. The blood supply is low, and the anastomotic branch of blood vessels is small and weak. What are the causes of femoral head necrosis? 1. Traumatic factors (Traumatic Reasons) are one of the important causes of femoral head necrosis. The uncoordinated movement of the elderly, coupled with osteoporosis, increases the number of fractures as the elderly population increases. One of the fractures most likely to affect the blood supply to the femoral head is a fracture of the femoral neck. The blood supply to the femoral head is supplied through an arterial ring at the base of the femoral neck. Fractures of the femoral neck inevitably result in vascular damage, which may lead to femoral head necrosis in 60-70% of cases. In adults, dislocation of the hip joint causes damage to the blood vessels supplying the femoral head, which leads to femoral head necrosis. In addition, slipped or dislocated epiphysis in children can also lead to femoral head necrosis. 2, Non-traumatic Reasons (Nontraumatic Reasons) are widely discussed. However, from many studies and clinical practice, there are two most definite causes: (1) Corticosteroid use: Some patients need hormone therapy to control immune abnormalities; in addition, some people believe in the prescriptions of charlatans, which may contain hormones. (2) Alcohol abuse: the amount of alcohol is not proportional to the rate of occurrence of femoral head necrosis. The occurrence of femoral head necrosis is related to the individual alcohol metabolic rate. (3) Other: gout, decompression sickness, Gaucher’s disease, hypercoagulable state, sickle cell anemia …… How to treat osteonecrosis of the femoral head? 1.Non-surgical treatment: It is applicable to patients with early femoral head necrosis. Generally doctors will advise patients to limit weight bearing to reduce the pressure on the femoral head. However, the effect is not obvious. Some medications are also taken, but they only relieve the symptoms, there is no special medicine for femoral head necrosis. In addition, there are physiotherapy methods such as electrical stimulation, the effect of which is subject to further study. 2.Surgical treatment: It is suitable for patients whose conservative treatment is not effective. Head preservation treatment, to preserve the patient’s femoral head. It mainly includes medullary decompression and bone grafting. Femoral head collapse can occur after clinical use of medullary decompression. It is also clinically controversial. Therefore, it is usually clinically indicated for patients with more pronounced pain. Osteotomy involves drilling from the lateral side of the femoral head to the necrotic area and cleaning the necrotic area with a scraping spoon. After cleaning, fibula is grafted to the necrotic area as a support. However, the success rate is not very high either and may only delay the collapse of the femoral head. Other surgical methods include bone grafting with blood supply and bone grafting. A bone graft with blood vessels is inserted into the femoral neck bone and anastomosed to the iliac vessels to improve the blood supply. However, this treatment method is more complicated and the success rate is not high. In China, some hip preservationists are studying osteotomy. After the osteotomy, the femoral head is rotated and the necrotic area is transferred to the non-weight-bearing area. 3. The most classic and fundamental method for patients with femoral head collapse and joint stenosis is total hip arthroplasty. This technology is very mature in China now. After successful surgery, normal life can be resumed.