Unipolar hemiarthroplasty versus bipolar hemiarthroplasty in the most elderly patients with displaced femoral neck fractures: a randomised, controlled trial

Hemiarthroplasty (HA) is generally considered to be the treatment of choice in the most elderly patients with a displaced fracture of the femoral neck. However, there is inadequate evidence to support the choice between unipolar HA or bipolar HA. The primary aim of this study was to analyse the outcome regarding hip function and health-related quality of life (HRQoL) in patients randomised to either a unipolar or bipolar HA. The secondary aim was to analyse the degree of acetabular erosion and its influence upon outcome. One hundred twenty patients with a mean age of 86 years and an acute displaced fracture of the femoral neck were randomly allocated to treatment by either unipolar or bipolar HA. Outcome measurements included hip function (Harris Hip Score, HHS), HRQoL (EQ-5D) and acetabular erosion. The patients were summoned at four and 12 months for follow-up. There were no significant differences between the groups regarding complications. The HHS scores were equal at both follow-ups, but there was a trend towards better HRQoL in the bipolar HA group at four months, EQ-5D (index) score 0.62 vs 0.54 (p = 0.06). Twenty percent of the patients in the unipolar HA group displayed acetabular erosion at the 12-month follow-up compared to 5% in the bipolar HA group (p = 0.03), and there were trends towards worse hip function and HRQoL among patients with acetabular erosion compared to those without: HHS scores 70.4 and 79.3, respectively (p = 0.09), and EQ-5D (index) scores 0.48 and 0.63, respectively (p = 0.13). Unipolar HA and bipolar HA appeared to produce equivalent clinical outcomes after one year, but the significantly higher incidence of acetabular erosion in the unipolar HA group may imply that bipolar HA should be the preferred treatment.