How to detect osteonecrosis of the femoral head among millions of diseases? Diagnosis can be made by one of the following tests: 1) X-ray: necrotic foci surrounded by sclerotic bands, segmental collapse, crescent sign, femoral head collapse but joint space maintenance. (2) MRI: T1WI, banded low signal; T2WI, double line sign; T2WI lipid suppression, high signal band around the circumference of the necrotic foci; T2WI lipid suppression, bone marrow edema in the femoral head and neck except for the focal area, and T1WI is banded low signal. (3) CT: well-defined necrotic foci with subchondral fractures. Femoral head necrosis, what to do clinically? 1, drug treatment: for early ONFH can be used anticoagulation, pro-fibrinolytic, vasodilator drugs, such as low-molecular heparin, prostaglandin, etc.. Application of drugs to inhibit osteolysis and increase osteogenesis, such as phosphate preparations, methyldopa, etc.. Depending on the situation of necrosis, drugs can be used alone or in combination with hip preservation surgery. 2, hip preservation surgery treatment hip preservation surgery treatment marrow core decompression or joint autologous bone marrow single nucleus cell implantation: it is still in the experimental stage and needs to be used with caution; lesion removal, bone graft with or without blood transport: the access of lesion removal includes trans-femoral greater trochanter, anterior trans-femoral head and neck junction opening and trans-femoral cartilage flap; osteotomy: there are trans-femoral greater trochanter femoral head and neck rotational osteotomy, trans-femoral rotor The osteotomy: there are rotational osteotomy of the femoral head neck via the greater trochanter and rotational osteotomy of the femoral head via the femoral rotor. The selection of tantalum rods should be cautious, and transcatheter intervention alone is not recommended. 3, artificial arthroplasty a considerable part of ONFH patients eventually to receive artificial arthroplasty, there are generally four kinds: ① surface replacement: limited indications, not suitable for necrosis volume is large, gold on the gold bearing surface complications make the application of the amount of decline. ② Femoral head replacement: limited indications due to the inability to predict the occurrence of pain and acetabular wear after surgery. ③Total hip arthroplasty with a short-stemmed femoral prosthesis: in development. ④Total hip arthroplasty: it is the most classic and models mature, the effect is definitely lasting artificial joint surgery, applicable to most of the stage IV and V ONFH patients, for middle-aged and young patients it is recommended to use wear-resistant load-bearing surface (tau to tau, tau to high cross-linked polyethylene), biological bone growing into the type of prosthesis. What are the treatment principles for different stages and subtypes of femoral head necrosis? ①Stage I and II, type M: perform follow-up, observation or comfort treatment. ②Stage I and II, type C: extracorporeal shock wave, medullary decompression or lesion removal, autologous bone marrow transplantation or compression osteotomy, and drug treatment. ③Stage I and II, type L1: focal removal, support bone graft (bone graft with blood vessels or blood transport) or compression bone grafting, and drug treatment; inversion osteotomy can be chosen for those <35 years old. (④Stage I and II, L2 and L3: lesion removal, support bone graft (with blood vessel or blood transport bone graft) or compression bone grafting; trans-femoral rotational osteotomy can be chosen for L2 type <35 years old. (⑤) Stage III: for those <50 years old, hip preservation is the main method, and the method is the same as ④; for those >50 years old, artificial arthroplasty can be chosen because of heavy pain and poor joint function. (6) Stage IVa and IVb: those <40 years old should try to preserve the hip; those >40 years old can choose artificial arthroplasty because of heavy pain and poor joint function. (vii) Stage IVc and V: artificial arthroplasty can be chosen because of heavy pain and poor joint function. Which groups of people are the frequent patients of femoral head necrosis? The high-risk groups for ONFH include: ① hip trauma: femoral head and neck fracture, acetabular fracture, hip dislocation, severe sprain of the hip or contusion with intra-articular hematoma; ② prolonged high-dose application of glucocorticoids; ③ long-term heavy alcohol consumption; ④ high coagulation and low fibrinolytic tendency and autoimmune disease, use of GCs; ⑤ history of decompression chamber work. How to stage femoral head necrosis? ONFH is classified according to clinical manifestations: ① preclinical (stage I): no symptoms and signs; ② early stage (stage II): no symptoms or only mild hip discomfort, including discomfort in the groin or greater trochanter, hip pain with strong internal rotation, and no significant impairment of joint movement; ③ pre-collapse (middle stage, stage III): more severe acute hip pain, mild claudication, limited internal rotation, and increased pain with strong internal rotation. (iv) Collapse stage (middle and late stage, stage IV): moderate to severe pain, obvious claudication, moderate limitation of joint flexion and internal rotation and abduction; (v) Osteoarthritis stage (late stage, stage V): severe pain, increased claudication, obvious limitation of joint activities (flexion, internal rotation, internal rotation), joint deformity (flexion and external rotation, internal rotation).