Longer hospital stay but similar one-year mortality and readmission after combined proximal humerus and proximal femur fragility fractures: a Propensity-Score–Matched Cohort Study

Abstract Background Fragility Proximal Humerus (PH) fractures are common and often associated with significant morbidity and mortality. Unlike Proximal Femur (PF) fractures, PH fractures are often omitted from established orthogeriatric multidisciplinary team (MDT) pathways. Combined Proximal Humerus and Proximal Femur fractures (PH&PF) are rare. Combined injuries would be expected to result in worse outcomes compared to isolated PH fractures due to greater injury burden. This study assessed outcomes between isolated PH and combined PH&PF fractures, exploring whether differences in care pathways may contribute to outcome. Methods A retrospective propensity score-matched cohort study was performed over a 2-year period identifying patients sustaining isolated fragility PH fractures and over a 5-year period identifying patients sustaining combined PH&PF fractures secondary to low-energy trauma. Propensity score matching was performed using age, sex, comorbidity burden (as defined by Charlson Comorbidity Index (CCI)), mobility status, cognitive impairment and fracture pattern. Primary outcome was 1-year mortality. Secondary outcomes included 1-year readmission and length of stay (LoS). Mortality was analysed using Firth logistic regression, readmission using clustered logistic regression, and LoS using Gamma regression with cluster-robust standard errors. Results Sixty-five patients were included following matching (42 PH, 23 PH&PF). Excellent covariate balance was achieved across all matched variables (all absolute standardised mean differences < 0.10). One-year mortality was 7.1% in the PH group and 13.0% in the PH&PF group (OR 1.93, 95% CI 0.38–9.88; p = 0.417). Readmission occurred in 33.3% and 26.1% of patients, respectively (OR 0.71, 95% CI 0.17–2.92; p = 0.615). Median hospital LoS was 4 days (IQR 0-18.3) for PH fractures and 17 days (IQR 10.5–44.5) for PH&PF fractures. Gamma regression estimated a two-fold increase in hospital LoS among patients with concomitant PH&PF fractures (length-of-stay ratio 2.03, 95% CI 0.98–4.22; p = 0.057). Sensitivity analyses incorporating calendar year yielded similar findings. Conclusions Despite a greater injury burden, patients with combined PH&PF fractures demonstrated equivocal 1-year mortality and readmission rates versus those with isolated PH fractures. These findings raise the possibility that access to established orthogeriatric MDT pathways may contribute to outcomes and support further prospective investigation into dedicated multidisciplinary care models for fragility PH fractures.