How to do the differential diagnosis of osteonecrosis of the femoral head? Many people are unclear, timely and accurate differential diagnosis of osteonecrosis of the femoral head is critical to the treatment of the disease. Femoral head necrosis disease is very harmful, if the disease is found early, it should be treated in time, do not let the condition deteriorate. For the differential diagnosis of femoral head necrosis, the diagnosis can be made from the following aspects: First, observe the changes in physical signs to see if muscle atrophy is a characteristic of traumatic femoral head necrosis. When femoral head necrosis occurs, muscle atrophy begins to occur, i.e., a decrease in muscle volume and tone, mainly in the muscles of the buttocks, thigh muscles, and calf muscles. Secondly, abnormal gait is caused by hip pain, femoral head deformation and collapse, pelvic tilt, or subluxation of the hip joint, which mainly manifests as progressive shortening limp. In the early stage, it can be intermittent slope shape, i.e. no lameness after resting and lameness after walking, and in the middle and late stage, it will be persistent lameness. Thirdly, whether there is pressure pain, generally there is obvious deep pressure pain around the femoral head, especially significant pressure pain on the stop of the adductor muscle. In addition, longitudinal percussion pain and activity pain are present in varying degrees. Fourthly, through auxiliary examinations, such as CT and MRI can be used as differential diagnosis.