Abstract
BACKGROUND: Femoral fractures are high-impact injuries commonly arising from traffic collisions, falls, and other trauma mechanisms. Surgical site infection (SSI) following fixation remains a major postoperative complication, amplified by soft-tissue disruption, environmental contamination, and prolonged hospitalization. Evidence on how mechanism of injury (MOI) moderates SSI risk, pathogen distribution, and antimicrobial resistance (AMR) patterns in trauma populations remains limited. METHODS: We conducted a 5-year retrospective cohort study (2020-2024) at a tertiary trauma centre including all operatively managed femoral fractures. MOI categories comprised traffic accidents, falls, sports injuries, violence, work-related trauma, and firearm injuries. Demographic, clinical, surgical, and microbiological data were obtained from a prospectively maintained registry. SSI was defined according to the 2018 AO/EBJIS Fracture-Related Infection (FRI) consensus criteria. Group comparisons used χ(2) or Fisher's exact tests, and multivariable logistic regression identified independent predictors. Infection-related reoperation and 1-year mortality were assessed with survival analysis. FINDINGS: Of 2891 patients, 249 developed SSI (8.6%). Gram-negative organisms predominated, with A. baumannii accounting for most isolates across MOI groups, while S. aureus was more common in younger and sports-related injuries. Resistance testing showed persistently high multidrug resistance (MDR, 66.2%), with declining trends in extensively drug-resistant (XDR) phenotypes and carbapenem resistance over time. Independent predictors of SSI included ASA ≥ 3, diabetes mellitus, preoperative anaemia, and operative duration > 90 min. SSI markedly increased reoperation rates and more than doubled 1-year mortality. CONCLUSION: MOI shapes both SSI risk and microbiological profiles following femoral fracture surgery. The dominance of Gram-negative organisms and high MDR burden highlight the need for MOI-specific prevention strategies and trauma-adapted antimicrobial stewardship.