Hip pain and/or limited motion due to osteoarthritis is often the primary symptom that patients present to orthopedics for consultation and treatment. Although the efficacy of total hip replacement is well recognized, the specific surgical operation is not exactly the same due to different primary diseases. Especially in adult patients with developmental dysplasia of the acetabulum (DDH), due to the abnormal development of the acetabulum, the surgery requires deepening and enlarging the acetabulum and reconstructing the center of hip movement; while the conventional replacement acetabular prosthesis, due to biomechanical abnormalities, is prone to postoperative dislocation of the prosthesis leading to surgical failure. Therefore, preoperative clarification of the primary disease and intraoperative treatment are very important for the prognosis of total hip replacement. Differential diagnosis of femoral head ischemic necrosis (AFHN) and DDH. The clinical symptoms of DDH and AFHN are similar, with the early stage showing vague pain when the affected hip is fatigued and resting pain as the disease progresses, accompanied by varying degrees of activity limitation or even claudication, and the late stage X-ray showing joint space narrowing, femoral head collapse or even dislocation. Especially for patients with Crowe type I and II DDH, the dislocation is not serious, so it is more difficult to distinguish them. The differentiation between the two lies in: (1) Medical history: AFHN patients are mostly middle-aged and elderly patients (over 50 years old) with a clear medical history, such as a history of hip trauma, a history of long-term heavy hormone use or alcohol consumption; DDH patients are relatively young, with a common onset between 20 and 50 years old, no obvious cause, and mostly progressive discovery of hidden pain in the affected hip. (2) Imaging: AFHN patients mostly have typical imaging manifestations, such as femoral head signal unevenness, crescent sign, femoral head collapse, etc., but the lesions are mostly limited to the femoral head and the acetabular changes are not obvious; DDH patients have obvious anatomical abnormalities in the acetabulum, manifesting as shallow and small acetabular development, insufficient inclusion of the femoral head, abnormal CE angle and Sharp angle, and cystic changes in both the femoral head and acetabulum on X-ray plain film. (3) Treatment measures: the main reason for the development of AFHN is the impaired blood supply to the femoral head, reducing weight-bearing in the early stage of the patient can slow down the progress of the disease, and the patient can be given symptomatic treatment with traditional Chinese medicine such as blood activation and circulation, and medullary core decompression implantation or vascular implantation often has certain efficacy; the mechanism of the development of DDH lies in the inadequate acetabular inclusion and imbalance of weight-bearing of the femoral head, so the efficacy of blood activation and circulation improvement is not obvious, and early therapeutic interventions Early therapeutic intervention is to improve acetabular inclusion, and pelvic osteotomy or femoral osteotomy may improve symptoms and control disease progression. In one case of DDH in this group, the patient was Crowe type I with an atypical medical history, no typical crescent sign and head collapse on preoperative X-ray, and only showed a slightly shallow and small acetabulum, which was misdiagnosed as AFHN for conventional total hip replacement surgery and led to prosthesis displacement under stress after surgery.