Comorbidity burden and fracture pattern as predictors of early postoperative medical complications following bipolar hemiarthroplasty for displaced femoral neck fractures: a retrospective cohort study

Postoperative medical complications substantially affect outcomes after bipolar hemiarthroplasty (BHA) for displaced femoral neck fractures, with an impact comparable to surgical factors. This study aimed to identify risk factors for postoperative medical complications, focusing on comorbidities, polypharmacy, and fracture pattern. This retrospective cohort study included 310 hips in 297 patients undergoing BHA. Baseline characteristics, comorbidities, and medication profiles were evaluated using the Charlson Comorbidity Index (CCI), Elixhauser Comorbidity Index (ECI), and comorbidity-polypharmacy score (CPS). The primary outcome was medical complications within 30 days. Multivariable logistic regression was used to identify independent predictors, and 1-year survival was assessed using Kaplan–Meier analysis. Medical complications occurred in 53.7% of hips, most commonly delirium (17.0%). In the CCI-based model, age at surgery (odds ratio [OR] 1.05; 95% confidence interval [CI], 1.01–1.08; p = 0.006), displaced transcervical fractures (AO/OTA 31B2.1–31B2.2) (OR 2.07; 95% CI, 1.18–3.61; p = 0.011), displaced basicervical fractures (AO/OTA 31B2.3–31B3) (OR 4.67; 95% CI, 1.45–15.00; p = 0.010), a medium CCI category (OR 3.58; 95% CI, 1.10–11.60; p = 0.034), and a very high CCI category (OR 12.80; 95% CI 2.27–72.10; p = 0.004) were independently associated with complications. In the ECI-based model, age (OR 1.04; 95% CI, 1.01–1.07; p = 0.016), displaced transcervical fractures (OR 1.88; 95% CI 1.10–3.22; p = 0.021), and displaced basicervical fractures (OR 4.71; 95% CI 1.50–14.80; p = 0.008) remained significant predictors. One-year survival was 94.2% and was significantly lower among patients with higher CCI scores. Comorbidity burden and fracture pattern are significant predictors of early postoperative medical complications after BHA for displaced femoral neck fractures. Incorporating these factors into preoperative risk stratification may facilitate optimized perioperative management and improve clinical outcomes.