I. Hip pain of unknown origin with occasional claudication. II. Idiopathic osteonecrosis has been clearly diagnosed in the contralateral hip joint, with mild pain on the affected side. III. There are clear causative factors, such as long-term or short-term heavy use of corticosteroids, excessive alcohol consumption, sickle cell anemia, history of Gaucher disease and decompression, or engagement in diving operations and pipeline workers. IV. After treatment of femoral neck fracture, hip dislocation, acetabular fracture, etc.