Higher risk of reoperation for bipolar and uncemented hemiarthroplasty

BACKGROUND AND PURPOSE Hemiarthroplasty as treatment for femoral neck fractures has increased markedly in Sweden during the last decade. In this prospective observational study, we wanted to identify risk factors for reoperation in modular hemiarthroplasties and to evaluate mortality in this patient group. PATIENTS AND METHODS We assessed 23,509 procedures from the Swedish Hip Arthroplasty Register using the most common surgical approaches with modular uni- or bipolar hemiarthroplasties related to fractures in the period 2005-2010. Completeness of registration (individual procedures) was 89-96%. The median age was 85 years and the median follow-up time was 18 months. RESULTS 3.8% underwent reoperation (any further hip surgery), most often because of implant dislocation or infection. The risk of reoperation (Cox regression) was higher for uncemented stems (hazard ratio (HR) = 1.5), mainly because of periprosthetic femoral fractures. Bipolar implants had a higher risk of reoperation irrespective of cause (HR = 1.3), because of dislocation (1.4), because of infection (1.3), and because of periprosthetic fracture (1.7). The risk of reoperation due to acetabular erosion was lower (0.30) than for unipolar implants, but reoperation for this complication was rare (1.7 per thousand). Procedures resulting from failed internal fixation had a more than doubled risk; the risk was also higher for males and for younger patients. The surgical approach had no influence on the risk of reoperation generally, but the anterolateral transgluteal approach was associated with a lower risk of reoperation due to dislocation (HR = 0.7). At 1 year, the mortality was 24%. Men had a higher risk of death than women (1.8). INTERPRETATION We recommend cemented hemiarthroplasties and the anterolateral transgluteal approach. We also suggest that unipolar implants should be used, at least for the oldest and frailest patients.