Background and purpose: Surgical site infection (SSI) after hip fracture surgery is a feared condition. We examined the trend in incidence of reoperation due to SSI up to 1 year following hip fracture surgery from 2005 to 2016 and risk factors of SSI by age, sex, comorbidity, type of fracture, and surgery.
Patients and methods: We conducted a population-based, nationwide cohort study using data from the Danish Multidisciplinary Hip Fracture Register (DMHFR). We included 74,771 patients aged 65 and up who underwent surgery from 2005 to 2016 for all types of hip fracture. We calculated net risk of reoperation using Kaplan–Meier method, and, with Cox regression, adjusted hazard ratios (HRs) with a 95% confidence interval (CI) for reoperation due to SSI.
Results: Overall, the 1-year net risk of reoperation due to SSI was 1.6%. The HR was higher for patients undergoing total/hemiarthroplasty surgery versus internal fixation (HR = 1.5; 95%CI 1.3–1.8) and lower for patients with per-/subtrochanteric fracture versus femoral neck fracture (HR = 0.6; CI 0.6–0.7). The risk of reoperation due to SSI decreased over time; HR was 0.7 (CI 0.5–0.8) for 2015–2016 compared with 2005–2006. Risk of reoperation decreased with increasing age; the HR was 0.8 (CI 0.7–1.0) in the more than 85-year-olds compared with 65–74-year-old patients. Charlson Comorbidity Index of ≥ 3 was associated with a higher risk of reoperation due to SSI, HR was 1.3 (CI 1.1–1.6).
Interpretation: The net risk of reoperations due to SSI in our study was lower than previously assumed. We identified several risk factors for increased risk of reoperation due to SSI, most noticeably treatment with arthroplasty vs. internal fixation, as well as younger age, high comorbidity burden, and femoral neck fracture diagnosis.