Total Hip Arthroplasty Using Metal Head on a Highly Cross-linked Polyethylene Liner / 대한고관절학회지

PURPOSE: This retrospective study was performed to evaluate the clinical results and measure polyethylene liner wear in total hip arthroplasty (THA) with highly cross-linked polyethylene. MATERIALS AND METHODS: Except for patients who had died or were unable to have follow-up at least 2 years, 60 of 78 hips that underwent THA were included this study. The mean age was 64.5 years (range, 25-81 years) and the mean body mass index (BMI) was 23.0 kg/m2 (18.1-32.3 kg/m2). Diagnosis at the time of the operation was osteonecrois of the femoral head in 28 hips, primary osteoarthritis in 14, hip fracture in 13, and other diseases in 5. The mean follow-up period was 3.8 years (2.1-7.1 years). Harris hip score (HHS) was reviewed before THA and at the last follow-up. On the anteroposterior pelvic radiographs, acetabular cup inclination and ante-version were also measured. The annual linear wear rate was measured using Livermore's method on the radiographs. RESULTS: The mean HHS was 60.1 (28-94) before operation and 90.4 (47-100) at the last follow-up. In the immediate post-operation, the average inclination and anteversion angles of the acetabular cups were 46.3degrees (standard deviation, +/-6.7degrees) and, 21.4degrees(+/-10.1degrees) respectively. The mean of the annual linear polyethylene wear was 0.079 mm/year (0.001-0.291 mm/year). Age, gender and BMI were not statistically related to linear polyethylene wear but the period of follow-up and the acetabular cup's inclination showed significant negative and positive correlation respectively. CONCLUSION: The wear rate of a highly cross-linked polyethylene was shown to correlate negatively with duration of follow-up. However, our study was based on a short-term follow-up, so a long-term follow-up study is necessary in the future.

Total Hip Arthroplasty Using AML(R) Prosthesis: Minimum 20-Year Follow-Up of the Patients / 대한정형외과학회잡지

PURPOSE: We reviewed the radiological outcomes and survival rate of the total hip arthroplasty (THA) with AML(R) (Anatomic Medullary Locking, DePuy, Warsaw, IN, USA) hip prosthesis on long-term follow-up. MATERIALS AND METHODS: From May 1988 to December 1990, 93 hip arthroplasties were performed on 77 patients in our hospital. In this study, 30 patients, of whom 41 hips underwent the procedure, were alive and able to be included. Follow-up was average of 21.4 years. The mean patient age was 45 years (35-60 years) at the time of operation. Of the hip procedures included in our study, the reasons for THA were osteonecrosis of the femoral head in 25 hips, rheumatoid arthritis in 3 and acetabular dysplasia in 2. We analyzed the wear rate of the polyethylene, osteolysis of the femur and acetabulum and stress shielding of the femur on the follow-up radiographs. In addition, we investigated the survival rate of the prosthesis and causes of revision in the last follow-up. RESULTS: The polyethylene wear rate of the surviving acetabular cup was 0.15 mm/yr. Acetabular osteolysis was detected in 33 hips and was mostly in zone 2 and 3. Femoral osteolysis was showed in 32 hips in zone 1 and 7. Stress shielding over grade 3 was found in 5 of 21 femoral stems in over 13.5 mm in diameter. The grade of stress shielding did not progress with follow-up. Of the 33 hips, 26 (63.4%) cups were revised for polyethylene wear and osteolysis. There were 6 (21%) femoral stems revised for osteolysis. CONCLUSION: The cause of a high revision rate of the prosthesis was polyethylene wear and osteolysis. We predict that THA using AML(R) prosthesis with wear-resistant bearing surfaces could increase the survival rate on long-term follow-up over 20 years.