Zules Oña Ricardo GabrielSusana Otero-RomeroJose Angel Rodrigo-PendásJoan Minguell-MonyartCarles Amat-MateuMayli LungXavier Martínez-GómezCristian Quintana-AlonsoEnric LimónOleguer Parés-Badell2026-02-092026-02-092026-01https://doi.org/10.1016/j.ajic.2025.12.016Background In early 2018, we detected an increase in surgical site infections (SSI) after total knee arthroplasty in a tertiary hospital in Barcelona. We implemented an infection prevention and control (IPC) intervention reinforcing preventive bundles and reorganizing surgical schedules for high-risk patients and senior surgeons. We aimed to identify SSI-associated factors and evaluate the IPC intervention’s impact. Methods We conducted a retrospective cohort study in 2018 with 90-day follow-up. SSI rates were compared pre- and post-intervention. Preintervention risk factors were assessed using Cox models. Differences in associated factor distributions were estimated. Kaplan-Meier and log-rank tests evaluated incidence, and a sensitivity analysis was stratified by American Society of Anesthesiologists (ASA) and National Nosocomial Infection Surveillance (NNIS) risk. Results Among 463 patients, overall SSI incidence was 0.52 per 1,000 patient-days. Incidence significantly declined postintervention (pre: 0.75; post: 0.26; P = .030). Obesity (HR: 3.63; 95% CI: 1.02-12.86) and afternoon surgery (HR: 3.02; 95% CI: 1.02-8.92) were associated. High ASA, NNIS risk, and inadequate prophylaxis significantly decreased (P ' .001). The intervention reduced SSI risk by 66% (HR: 0.34; 95% CI: 0.13-0.94; P = .037). A nonsignificant reduction was seen in high-risk strata. Conclusions Our study showed the impact of an IPC intervention addressing associated factors and significantly reducing SSI incidence rates.enHealth care-associated infectionsInfection controlKnee replacement arthroplastyNosocomial infectiontext::journal::journal article