To verify that CT scan and X-ray can predict the collapse of the necrotic femoral head before hip arthroplasty and effectively guide the surgical management.

Osteonecrosis of the femoral head (ONFH) is a common and frequently occurring disease. The main clinical manifestations are hip pain and dysfunction. The etiology and pathogenesis of ONFH caused by various reasons are the problems that have not been solved yet in the field of orthopedics. If want to achieve satisfactory therapeutic effect, surgical choice is essential. It is very important for prognosis to master the indications of operation and take appropriate treatment measures, especially the great difference between palliative surgery and hip arthroplasty.

To determine whether the femoral head collapses and the degree of collapse of the articular cartilage of the femoral head can help physicians to select an optimal surgical plan. Chinese scholars commonly believe that if the femoral head collapse is less than 2 mm, investigators can choose autologous bone graft, allogeneic bone graft and other palliative surgery. If the femoral head collapse is more than 2 mm, investigators can choose total hip arthroplasty. However, above standard has not been extensively accepted worldwide.

Inclusion Criteria:

• Unilateral ONFH confirmed preoperatively (FICAT stages III and IV; Appendix 1)14
• Unilateral total hip arthroplasty
• Age range: 32-68 years
• Irrespective of sex
• Sign the informed consent

Exclusion Criteria:

• Infection
• Tuberculosis
• Tumor
• Severe osteoporosis