NO BENEFIT OF EXTENDED ORAL ANTIBIOTICS FOLLOWING TWO-STAGE REIMPLANTATION TOTAL KNEE ARTHROPLASTY FOR PERIPROSTHETIC JOINT INFECTION

Introduction & Aims The evidence and role of extended oral antibiotics (EOA) following two-stage reimplantation is conflicting and unclear. Therefore, the purpose of this study is to evaluate the impact of extended oral antibiotics following two-stage reimplantation total knee arthroplasty (TKA) on 1) prosthetic joint infection (PJI); 2) subsequent revision; and 3) emergency room visits and hospital readmissions. Methods Using an insurance claims database, we identified a cohort of 2,181 uncomplicated two-stage reimplantation TKA for PJI between 2016 and 2022, defined as no additional PJI-directed surgery between stages and at least 2 years of post-reimplantation enrollment. Stage-2 reimplantation was required to occur 8 to 18 weeks after stage one. Patients were stratified using pharmacy claims into an EOA group, defined as ≥60 days of qualifying oral antibiotic therapy within 90 days after reimplantation with early postoperative exposure confirming treatment initiation (n=473), and a non-EOA group, defined as patients who did not meet EOA criteria (n=1,708). The overall median interval from stage one to two was 84 days (IQR 70 to 98), with no between-group difference (p>0.05). The primary outcome of interest was recurrent PJI at one year. Secondary outcomes included PJI at 90 days and two years, 90-day emergency department (ED) visits, 90-day readmission, and re-revision. Multivariable logistic regression analyses were adjusted for age, sex, Elixhauser Comorbidity Index (ECI), morbid obesity, type II diabetes mellitus, tobacco use, and inflammatory arthritis. Results EOA was not associated with lower recurrent infection at 90 days (5.5 versus 4.1%, P=0.24), one year (7.8 versus 8.3%, P=0.80), or two years (10.6 versus 10.8%, P=0.94). There was a nonsignificant trend toward fewer reoperations within 90 days in the EOA group (P=0.10). There were no differences in 90-day ED visits, 90-day readmissions, or one-year re-revisions between groups. Multivariable analysis confirmed no association between EOA and recurrent PJI at 90 days (odds ratio [OR]: 0.8, P=0.26), one year (OR: 1.1, P=0.59), or two years (OR: 1.1, P=0.70). Male sex (OR range: 2.1 to 2.2, P<0.01) and inflammatory arthritis (OR range: 1.9 to 2.3, P≤0.05) were consistently associated with increased PJI risk. Conclusions Extended oral antibiotic therapy following uncomplicated two-stage reimplantation did not reduce the risk of subsequent infection. While EOA did not adversely impact reoperations, ED visits, or hospital readmissions, its routine use in the absence of demonstrated benefit is not conducive to good antibiotic stewardship.