Worldwide, it is expected that 6.3 million patients will sustain a hip fracture in 2050. Hemiarthroplasty is commonly practiced for displaced femoral neck fractures. The choice between unipolar (UH) or bipolar (BH) hemiarthroplasty is still controversial. The objective of this study was to assess the effect on hip function of BH compared to UH for a displaced femoral neck fracture in elderly patients.

We conducted a systematic review and meta-analysis of randomized controlled trials comparing BH to UH. Data sources were Medline, Embase, Cochrane Library and Web of Science. All data was pooled in Review Manager (RevMan) version 5.3 software. Selection of the studies included, data abstraction, data synthesis, risk of biais and quality of evidence evaluation was done independently by two authors. Our primary outcome was postoperative hip function. Secondary outcomes were health-related quality of life (HRQoL), acetabular erosion and postoperative complications.

13 randomized controlled trials (n=2256) were eligible for the meta-analysis. There was no difference in hip function scores (standardized mean difference of 0.33 [−0.09–0.75, n=864, I²= 87%,]). Patients with bipolar heads had higher Health-Related Quality of Life scores than patients with unipolar heads (mean difference in EQ-5D scores of 0.12 [0.04–0.19, n=550, I²= 44%]). The use of BH decreased the incidence of acetabular erosion (relative risk of 0.37 [0.17–0.83, n=525, I²= 0%]). There was no relative risk difference for mortality, dislocation, revision and infection.

Due to the high heterogeneity between the studies included, it is still unclear whether patients undergoing BH have better hip function than patients undergoing UH. Although, health-related quality of life (HRQoL) may be improved. Future research could be conducted to determine whether a BH offers a better quality of life than UH to geriatric patients undergoing surgery. More precise assessment scores could be developed to better evaluate postoperative outcomes.