Abstract
BACKGROUND AND PURPOSE: Over the past 20 years, several changes in treatment policy and treatment options have taken place regarding hip replacement. For this reason, we wanted to investigate the results after hip replacement in terms of revision rate, during a 21-year period among hip replacements reported to the Norwegian Arthroplasty Register. METHODS: 110,882 primary total hip replacements were reported to the Norwegian Arthroplasty Register from 1987 through 2007. Risk of revision during the time periods 1993-1997, 1998-2002, and 2003-2007 was compared to that of the reference period 1987-1992. Adjusted Cox regression analyses were performed to compare the risk of revision in different time periods and extended analyses were done to investigate revision within the first postoperative year and after the first year. RESULTS: There was an overall reduced risk of revision in the time periods 1993-1997, 1998-2002, and 2003-2007 compared to the reference period: RR = 0.81 (95% CI 0.77-0.86), 0.51 (CI 0.47-0.55), and 0.77 (CI 0.68-0.85), respectively. The improved results were due to a marked reduction in aseptic loosening of the femoral and acetabular components in all time periods and in all subgroups of prostheses. A change in the timing of revision took place, with more early revisions and fewer late revisions in the later time periods. Revision due to dislocation and infection increased over time. INTERPRETATION: The risk of revision decreased during the study period, due to fewer cases of aseptic loosening of prosthetic components. The best results were obtained with the use of cemented prostheses. Prevention of dislocation and infection should be a major goal in the future, as revision due to these causes increased during the study period.