Factors associated with surgical site infection after ankle fracture fixation: a retrospective study in northern Sweden
TL;DR
Smoking, initial external fixation, and longer operative time were associated with higher risk of infection, while ASA estimate was imprecise and support perioperative risk mitigation.
Abstract
Background and purpose Ankle fractures are common, and open reduction and internal fixation (ORIF) is standard treatment for unstable injuries. Surgical site infections (SSI) remain a significant clinical challenge. We aimed to estimate incidence and to identify patient- and treatment-related factors associated with SSI after ankle ORIF. Methods In this retrospective cohort, we included all adults (≥ 18 years) who underwent ankle ORIF at 2 trauma centers in northern Sweden from 2015 to 2024. Data from medical records covered demographics, comorbidities, injury characteristics, surgical details, and peri/postoperative care. The primary outcome was incidence of SSI and the secondary outcome was independent factors associated with SSI. SSI was defined as an infection occurring at or near the surgical incision within 30 days after surgery or up to 1 year later in the presence of an implant. Results We included 781 patients (mean age 54 years; 61% women). SSI occurred in 11%; 27% of infections underwent revision surgery, and 39 infections (43%) were categorized as fracture-related infection (FRI). Other complications included urinary tract infections (2.2%), pneumonia (0.8%), deep vein thrombosis (0.5%), and pulmonary embolism (0.4%). In adjusted analyses, higher odds of SSI were observed with smoking (aOR 2.3, 95% confidence interval [CI] 1.1–4.8, P = 0.02), initial external fixation (aOR 5.6, CI 1.7–17.6, P = 0.004), and longer operative time (OR per minute 1.0, CI 1.0–1.0, P = 0.004). The American Society of Anesthesiologists (ASA) class estimate suggested increased risk but was imprecise (aOR 9.7, CI 1.0–93.6, P = 0.049). Age, sex, and open fracture were not associated with SSI in the adjusted model. Conclusion After ankle ORIF, SSI occurred in 11%. Smoking, initial external fixation, and longer operative time were associated with higher risk of infection, while ASA estimate was imprecise. These findings support perioperative risk mitigation (e.g., smoking cessation and operative efficiency) and motivate study of physiological risk (ASA).