Concomitant Polytrauma in Fall-Related Proximal Humerus Fractures: A Fracture-Subtype-Stratified Analysis of In-Hospital Outcomes

Objectives: To determine whether concomitant polytrauma is independently associated with worse in-hospital outcomes among fall-related proximal humerus fracture (PHF) patients and whether fracture subtype is associated with heterogeneity in this association. Methods: Retrospective cohort study using the American College of Surgeons Trauma Quality Program Participant Use File (ACS TQP-PUF; 2019–2022). Adults with PHF and a fall mechanism were included. Multivariable logistic regression adjusted for age, sex, the five mFI-5 components, anticoagulant use, and calendar year. Non-home discharge (NHD) was restricted to survivors. Sensitivity analyses used 1:1 PSM (all primary covariates in propensity model; post-matching SMDs assessed) and restriction to ground-level falls. Results: Among 63,995 fall-related PHF patients (70.5% female; 75.8% aged ≥65 years), 3884 (6.1%) met polytrauma criteria (ISS ≥ 16); polytrauma patients were more often male (45.1% vs. 28.5%) and slightly younger (mean age 69.3 vs. 72.0 years). Polytrauma was independently associated with in-hospital mortality (aOR 7.05, 95% CI 6.14–8.09) and non-home discharge among survivors (aOR 1.95, 95% CI 1.79–2.12; crude 72.0% vs. 64.6%). ICU utilization (aOR 13.25, 95% CI 12.34–14.22) and any complication (aOR 3.41, 95% CI 3.07–3.79) are reported as descriptive markers subject to triage and ascertainment bias, respectively. The ICD-10 subtype-stratified mortality aORs ranged from 3.36 to 8.28 across five strata (exploratory; no formal interaction test performed). PSM (3884 pairs; n = 7768) and ground-level fall restriction produced estimates consistent with the primary analyses. Conclusions: Concomitant polytrauma was independently associated with substantially higher in-hospital mortality and non-home discharge after fall-related PHF, identifying a high-risk subgroup that warrants closer clinical attention.