Rates of Extended Oral Antibiotic Prophylaxis After Primary Total Knee Arthroplasty Among High-Risk and Standard-Risk Patients: 2009 to 2022.

Background: Recent evidence suggests extended courses of oral antibiotics (EOA) after total hip arthroplasty and total knee arthroplasty (TKA) may reduce the risk of periprosthetic joint infection in high-risk patients. EOA rates after total hip arthroplasty have risen significantly. However, there is a lack of epidemiologic data on EOA prophylaxis following TKA. Therefore, we investigated national trends in EOA prophylaxis for primary TKA and whether these rates were reflective of changes in patient risk or prescribing practices.

Methods: Adult patients undergoing TKA between 2009 and 2022 were identified in a national insurance claims database. An EOA was defined as a 7 to 14-day course of a first-generation cephalosporin, cefdinir, clindamycin, doxycycline, or trimethoprim-sulfamethoxazole filled between 5 days preoperatively and 3 days postoperatively. Annual EOA rates were calculated and stratified by preoperative periprosthetic joint infection risk. Multivariable logistic regression was used to explore whether rates reflected changing patient characteristics. Future rates were predicted with time-series forecasting.

Results: We identified 712,212 eligible TKA cases. EOA rates rose from 0.91% in 2009 to 7.95% in 2022. Rates increased by 686% among standard-risk patients and 786% among high-risk patients. Logistic regression models using patient comorbidities could not account for changes in EOA rates. EOA rates were projected to rise to 18.3% by 2030.

Conclusions: Rates of EOA prophylaxis after TKA rose significantly from 2009 to 2022. This trend could not be explained by changing patient characteristics, suggesting widespread changes in antibiotic prescribing practices, which may be reflective of recent studies favoring EOA use. There is a need for further high-quality research examining the safety, efficacy, and role of EOA prophylaxis in the primary TKA patient population.