RESULTS OF PRIMARY CHARNLEY TOTAL HIP REPLACEMENT HAS IMPROVED OVER THE YEARS IN NORWAY

Abstract

Background: During the 1990s a change in operative technique for primary hip replacement took place in Norway. This study was designed to measure the revision rate in different time periods in cemented Charnley total hip replacements reported to the Norwegian Arthroplasty Register.

Patients and methods: 26 873 primary cemented Charnley total hip replacements reported to the Norwegian Arthroplasty Register in the time periods 1987–91, 92–96, 97–01 and 2002–05 were studied. Only hips with Palacos and Simplex cements with and without antibiotic were studied. To compare the time periods Kaplan Meier analysis was used. To adjust for differences in approach to the hip, age, sex and use of systemic antibiotic prophylaxis Cox regression was used.

Results: There was 28 % less risk of revision due to all causes in the time period 1997–01 compared to 1987–91 (RR=0.72 (95% CI 0.60–0.86), p< 0,001). There was inferior result in the time period 1992–96 compared to 1987–91, but from 1997 there has been an improvement of results due to fewer aseptic loosenings of the femoral component (RR 0.44 (95% CI 0.35–0.56), p< 0.001). There was however more luxations in the later period, and there was no improvement in revisions due to aseptic loosening of the acetabular component.

Conclusion: There has been an improvement in revision rate of the cemented Charnley prosthesis the last two time periods, due to fewer aseptic loosenings of the femoral component. The reason is probably better technique of component placement and better cementation technique. In the future prevention of luxation and better cementation technique of the acetabulum should also be emphasised.