Predictors of mortality after isolated distal humerus fractures in older adults

Distal humerus fractures (DHFs) in older adults can have significant clinical consequences. Prior mortality estimates are broad and confounded by concomitant injuries. The purpose of this study was to characterize 1- and 2-year mortality after isolated DHFs in older adults and identify predictors of survival, including comorbidity burden, operative status, and preinjury ambulation ability. We hypothesized that mortality would parallel that of other upper extremity fractures and be primarily influenced by baseline health and functional independence. We conducted a retrospective cohort study at a level I trauma center. Patients aged ≥55 years with Orthopaedic Trauma Association/Arbeitsgemeinschaft für Osteosynthesefragen 13A, 13B, or 13C DHFs from 2017-2024 were included for analysis. periprosthetic and pathologic fractures, non-index presentation, and all concomitant upper and lower-extremity or clinically significant spinal fractures. Demographics, comorbidities, baseline ambulation status, fracture characteristics, and treatment method were collected. Mortality at 1 and 2 years was assessed with Kaplan-Meier methods. Cox proportional hazards regression models adjusted for the Charlson Comorbidity Index (CCI). Fragility index (FI) and fragility quotient were calculated for operative status and ambulation comparisons. Eighty-two patients met the inclusion criteria. Kaplan-Meier-adjusted mortality was 13.4% at 1 year and 19.5% at 2 years. Patients who underwent operative intervention had lower 2-year mortality than nonoperative patients (9.3% vs. 30.8%), but operative status was not independently associated with mortality after CCI adjustment. Preinjury ambulation ability was strongly associated with survival. Community ambulators had significantly lower mortality at 1 year (2.2% vs. 27.0%) and 2 years (4.4% vs. 32.4%) compared with noncommunity ambulators, and ambulation remained protective in adjusted models. CCI independently predicted mortality across all analyses. Fragility analysis showed operative versus nonoperative outcomes were statistically fragile (FI 1), while preinjury ambulation status was robust (FI 4-7). In older adults with isolated DHFs, mortality at 1 and 2 years is substantial. Comorbidity burden and preinjury ambulation are strong predictors of mortality. Operative treatment was not independently associated with mortality and likely reflects surgeon selection bias for healthier patients. Ambulation status remaining significant on adjusted models highlights that it captures aspects of physiologic reserve not reflected in CCI. Incorporating ambulation status into treatment planning may improve risk stratification and counseling. Further prospective studies could determine whether operative intervention mitigates the physiologic consequences of immobilization in functionally dependent patients.