Revision Risk of Unipolar and Bipolar Hemiarthroplasties in the Dutch Arthroplasty Register

Abstract

BackgroundHemiarthroplasty (HA) for hip fractures can be performed with a unipolar or bipolar head. We describe the use of unipolar and bipolar HA after a hip fracture in the Netherlands and determined revision rates and risk factors. MethodsAll HAs for an acute hip fracture registered in the Dutch Arthroplasty Register (LROI) during 2007 to 2021 were included; 44,127(88%) unipolar and 6,013(12%) bipolar HAs. Competing risk survival analyses were performed with revision for any reason as the endpoint. Multivariable Cox regression analyses were performed adjusting for patient and surgery-related factors. ResultsThe 1-year, 5-year, and 10-year revision rates were comparable for unipolar and bipolar HA. Cox regression analysis showed a hazard ratio of 1.2 (95% confidence interval (CI) 1.0 to 1.4)) after adjustment for confounders for bipolar heads. In cases of a cemented stem, the 1-year cumulative incidence of revision was lower (1.5% (CI 1.4 to 1.7%) compared to uncemented stems (2.4% (CI 2.1 to 2.7%); uncemented stems showed higher risks for revision after adjustment compared to cemented stems (hazard ratio 1.4 (CI 1.2 to 1.5)). The anterior, antero-lateral, and straight-lateral approach showed lower risk for revision compared to the postero-lateral approach. ConclusionThe revision rate for bipolar HA and unipolar HA was comparable. However, after adjustment for potential confounders the risk for revision showed an estimated 20% increased revision risk for bipolar heads, although not statistically significant. For both head types, the risk for revision was significantly higher when an uncemented stem was chosen or the postero-lateral approach was used.