Extended oral antibiotic prophylaxis and PJI-free survivorship after primary total knee arthroplasty

Recent evidence has emerged supporting the use of extended oral antibiotic (EOA) prophylaxis after primary total knee replacement (TKA) to reduce periprosthetic joint infection (PJI) in high-risk patients. However, much of the evidence stems from single-institution series with limited sample sizes. This study aimed to explore the impact of EOA on complications and infection-free survivorship in a large cohort of patients after primary TKA.

A large national database was used to identify patients undergoing primary TKA from 2015 to 2022. Patients receiving 7-14 days of EOA were identified. Propensity-score matching, based on patient comorbidities, was used to match patients who received EOA and to control patients who did not. Three cohorts were created: any-risk, high-risk, and standard-risk. Complications at 90-days were assessed with univariate analysis and survivorship free of PJI to 2 years was analyzed with the Kaplan-Meier method and cox regression.

We identified 5,701 patients who received EOA: 3,628 (64%) with high-risk comorbidities and 2,073 (36%) standard risk. There were no significant reduction in hazard of PJI at 90-days (any-risk: HR: 1.65, 95% CI: 0.90-3.04, P = 0.11; high-risk: HR: 1.37, 95% CI: 0.69-2.70, P = 0.4; standard-risk: HR: 1.51, 95% CI: 0.53-4.26, P = 0.4), 1 year (P > 0.07), or 2 years (any-risk: HR: 1.42, 95% CI: 0.98-2.05, P = 0.065; high-risk: HR: 1.14, 95% CI: 0.76-1.73, P = 0.5; standard-risk: HR: 1.51, 95% CI: 0.76-2.98, P = 0.2) with EOA administration.

EOA prophylaxis was not associated with improved PJI-free survivorship at any measured time point following primary TKA in either high-risk or standard-risk risk patients. Given the observed widespread use of EOA, our study highlights the need for further investigation to delineate what specific populations may benefit from EOA prophylaxis.