EXTENDED ORAL ANTIBIOTIC PROPHYLAXIS FOLLOWING ASEPTIC TOTAL KNEE ARTHROPLASTY REVISION NOT FOUND TO REDUCE PERIPROSTHETIC JOINT INFECTIONS THROUGH FIVE YEARS

INTRODUCTION & AIMS Periprosthetic joint infection (PJI) following revision total knee arthroplasty (TKA) occurs in 5-9% of patients. Despite growing use of extended oral antibiotic (EOA) prophylaxis in high-risk patients, evidence regarding its effectiveness remains mixed. We evaluated PJI risk following revision TKA with and without EOA prophylaxis. METHODS Patients undergoing first-instance aseptic revision TKA were identified in the 2010-2023Q1 PearlDiver dataset. EOA prophylaxis was defined as oral antibiotic prescription >24 hours and <14 days, initiated within the first postoperative week. Patients with any non-joint infection during the first postoperative week were excluded to ensure antibiotics were prescribed with prophylactic intent. Patients receiving EOA prophylaxis were matched 1:4 to controls based on age, sex, and Elixhauser comorbidity index (ECI). Median follow-up was 3.42 years in the EOA cohort, and 5.13 years in the no-EOA cohort. Adjusted time to periprosthetic joint infection (PJI) was evaluated using Cox proportional hazards models controlling for high-risk comorbidities (smoking, BMI≥35kg/m2, diabetes, chronic kidney disease, autoimmune disorders) at 90 days, 6 months, 1 year, 2 years, and 5 years. Secondary infections occurring 7–90 days postoperatively were compared using multivariable logistic regression, adjusted for the same covariates. RESULTS Of 95,222 aseptic revision TKA cases identified, 4,768 (5.0%) received EOA. After matching, there was no significant difference in PJI risk between groups through five years postoperatively (p>0.05 for all). In the 7-90 day postoperative period, the EOA cohort had lower odds of pneumonia (OR=0.61, p=0.013), urinary tract infection (UTI, OR=0.77, p=0.020), superficial surgical site infection (SSI, OR=0.71, p=0.009), and hospital readmission (OR=0.79, p=0.001), without increased odds of C. difficile colitis. CONCLUSION EOA prophylaxis following aseptic revision TKA was not associated with reduced odds of PJI out to five-years. However, EOA was associated with lower odds of 7-90-day pneumonia UTI, SSI, and readmissions, suggesting possible secondary benefits.