EXETER AND CHARNLEY ARTHROPLASTIES WITH BONELOC OR HIGH-VISCOSITY CEMENT - COMPARISON OF 1,127 ARTHROPLASTIES FOLLOWED FOR 5 YEARS IN THE NORWEGIAN ARTHROPLASTY REGISTER

During the years 1991-1994, the Norwegian Arthroplasty Register record ed 1,324 primary hip arthroplasties implanted with the Boneloc cement. We have compared the survival until revision due to aseptic loosening for Charnley (n 955) and Exeter (n 172) prostheses. The Boneloc cemen ted hips were also compared with high viscosity cemented hips implante d during the same period. In the Boneloc cemented group, the estimated probability of survival at 4.5 years of a Charnley femoral component was 74% and for an Exeter femoral component 97% (p < 0.0001), Using a Cox regression model with adjustment for age, gender, type of cement, systemic antibiotic and stratified for diagnosis, an 8 times higher ri sk of revision was found in Boneloc cemented Charnley femoral componen ts than in Exeter femoral components (p < 0.0001). For the acetabular components, the difference between the Charnley and Exeter components with Boneloc cement was not statistically significant, In both the Cha rnley and the Exeter prostheses, the high viscosity cemented component s had significantly better survival than the Boneloc cemented componen ts. The Cox regression model showed that a Boneloc cemented Charnley f emoral component had a 14 times higher risk of revision than a high vi scosity cemented component (p < 0.0001), and for Exeter femoral compon ents a 7 times higher revision risk was found in the Boneloc cemented components (p=0.003). Our results confirm the previously reported infe rior results of Charnley prostheses implanted with Boneloc cement and inferior results of Boneloc cemented Exeter prostheses as well, but le ss pronounced than for Charnley prostheses.