The difference between femoral head necrosis and femoral head bone marrow edema syndrome can be distinguished from the pathological basis of the disease, symptoms, auxiliary examination and other aspects. 1. Pathological basis: the destruction of blood supply to the femoral head is the most important pathological basis of femoral head necrosis. Bone marrow edema of femoral head syndrome is based on osteoporosis of hip joint. 2. Symptoms: Necrosis of femoral head manifests as pain or soreness in the hip or groin area, which can be relieved after resting, and in the later stage, the femoral head collapses and the pain intensifies, which may lead to difficulty in walking or claudication. Bone marrow edema of the femoral head syndrome manifests as progressive hip pain, claudication, limited hip rotation, which is not relieved after rest. 3. Auxiliary examination: X-ray of femoral head necrosis typically shows that the density of femoral head is changed, the arrangement of bone trabeculae is disordered or sparse, and there may be a curved hyaline band, i.e., “half-moon sign”, and the joint space is narrowed in the late stage. In femoral head bone marrow edema syndrome, the X-ray manifestation is bone atrophy, normal joint space, blurred trabecular structure, but no cystic changes and meniscus sign. Necrosis of the femoral head and bone marrow edema of the femoral head syndrome are two different diseases, with different pathologic bases and different treatments and prognoses. If hip pain occurs, it should be promptly consulted and dynamically followed up.