No Improvement in Infection or Complication Rate With Extended Oral Antibiotic Prophylaxis After Primary Total Joint...

Periprosthetic joint infection (PJI) leads to increased complications and cost after total hip and knee arthroplasty (THA and TKA). Extended oral antibiotic prophylaxis (EOA) has attracted interest as a measure to prevent PJI among high-risk patients, but efficacy and risks of additional complications are uncertain. The goal of this retrospective cohort study was to evaluate these aspects of EOA in THA and TKA.

Adult patients who underwent primary THA or TKA between 2015 and 2025 were abstracted from an institutional database. The EOA protocol was a 7-day course of oral antibiotics directly following surgery given based on the discretion of the treating surgeon. Patients were extracted into two cohorts corresponding to whether they did or did not receive EOA. The cohorts were matched 1:4 on age, sex, and comorbidity. The incidence rate of PJI, along with various other complications, was assessed via univariate and multivariable analysis with Bonferroni correction of P < 0.004 applied. A total of 2,935 (1,205 THA; 1,730 TKA) patients were included following the inclusion criteria and matching. There were 587 (229 THA; 358 TKA) of these patients were in the EOA cohort, while 2,348 (976 THA; 1,372 TKA) were not.

After EOA, PJI rates did not significantly differ from non-EOA patients at 90 days (P = 0.366) and 1 year (P = 0.254), even among morbidly obese patients (P > 0.05). Receiving EOA was not a significant independent predictor of PJI after multivariate Cox hazards regression (P = 0.25). The 90-day postoperative adverse events did not differ significantly between cohorts (P > 0.05 for all).

In this retrospective single-center cohort study, no evidence was found that EOA prophylaxis provides benefit after THA or TKA. While adverse events were not elevated, the lack of demonstrated improvement in outcomes challenges the rationale for routine use of EOA in high-risk patients and underscores the need for prospective studies to define its role.