Unipolar versus bipolar hemiarthroplasty for displaced femoral neck fractures: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND Whether bipolar hemiarthroplasty (BH) for displaced femoral neck fractures has benefit over unipolar hemiarthroplasty (UH) remains controversial. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the relative effects between BH and UH. METHODS A systematic literature search (up to April, 2014) was conducted to include RCTs comparing BH with UH for displaced femoral neck fractures. Two authors independently assessed methodological quality of the included studies and extracted data. Surgical information and postoperative outcomes were analyzed. RESULTS A total of 10 RCTs including 1,190 patients were indentified. Our results demonstrated that BH was associated with similar or better outcomes in hip function, hip pain, and quality of life while with a higher cost compared with UH. Moreover, there were no significant differences between BH and UH with regard to operation time, blood loss, blood transfusion, hospital stay, mortality, reoperation, dislocation, and complications. BH could significantly decrease the incidence of acetabular erosion at 1 year follow-up compared with UH (RR = 0.24, 95% confidence interval (CI) = 0.06 to 0.89, P = 0.03), but no significant difference was observed at 4 months, 2 years, and 4 years follow-ups. CONCLUSIONS Based on the current evidence, BH is not superior to UH in terms of surgical information and postoperative results. Despite similar or better clinical outcomes compared with UH, BH with a higher cost could not decrease long-term acetabular erosion rate.