Functional Outcomes Following Bipolar Hip Hemiarthroplasty via the Direct Anterior Approach Versus Posterior and Direct Lateral Approaches: A Retrospective Cohort Study

OBJECTIVES: To compare functional recovery and length of hospital stay in patients undergoing bipolar hip hemiarthroplasty (BHH) for displaced femoral neck fractures using the direct anterior approach (DAA) versus the posterior approach (PA) and direct lateral approach (DLA). METHODS: Design : Retrospective cohort study using a prospectively maintained hip fracture registry Setting: Single tertiary care institution in Singapore. Patient Selection Criteria: Patients aged 60 years and older who underwent BHH for displaced femoral neck fractures (OTA/AO 31-B) between 2020 and 2023 were identified from the institutional hip fracture registry. Outcome Measures and Comparisons: Functional outcomes were assessed using the Modified Barthel Index (MBI; higher scores indicate better independence) and Parker Mobility Score (PMS; higher scores indicate better mobility) at discharge, 6 months and 12 months. Mobility status, length of stay, postoperative complications, reoperation and 1-year mortality were evaluated. Outcomes were compared between DAA and PA after propensity score matching, with an exploratory comparison to the DLA. RESULTS: A total of 504 patients were identified; 400 PA, 79 DAA and 25 DLA. After matching, 67 DAA cases and 134 PA cases were analysed. Age and sex distribution were similar between DAA and PA groups (80.7 ± 6.3 vs 81.1 ± 6.5 years, p = 0.655; female: 79.1% vs 75.4%, p = 0.556). The DAA group demonstrated a smaller decline in MBI from premorbid baseline to discharge as compared with the PA group (DAA: -49.85 ± 17.88 vs PA: -55.47 ± 18.90, 95% CI: 0.11 to 11.13, p=0.045). No significant differences were observed between the DAA and PA groups in changes from premorbid to 12-month MBI (DAA: -23.97 ± 27.46 vs PA: -18.52 ± 26.38, 95% CI: -13.67 to 2.78, p=0.193) or from premorbid to 12-month PMS (DAA: -2.72 ± 2.90 vs PA: -2.18 ± 2.46, 95% CI: -1.37 to 0.29, p=0.198). Length of stay (DAA: 9.88 ± 5.08 vs PA: 10.20 ± 5.20 days; p = 0.684) and 1-year mortality (DAA: 3.0% vs PA: 8.2%; p =0.156) were comparable between DAA and PA groups. CONCLUSIONS: DAA for BHH was associated with better early functional recovery at hospital discharge than PA. However, this advantage did not persist at 12 months, with no significant differences in functional outcomes, length of hospital stay, or 1-year mortality between DAA and PA groups. LEVEL OF EVIDENCE: III