Table 1 Rate of infection within one year based on number of risk factors and receipt of extended oralantibiotic prophylaxis by procedure


Published 9/2/2021
Ariel DeMaio

Extended Oral Antibiotic Prophylaxis Protocol Is a Cost-effective Tool for Preventing PJI

Periprosthetic joint infection (PJI) is a dreaded complication after total knee arthroplasty (TKA) and total hip arthroplasty (THA), particularly for high-risk patients who have increased susceptibility to infection. Research has identified several surgical and host factors that predispose patients to PJI following these procedures, but only limited evidence demonstrates that preoperative optimization minimizes risk.

In a study of nearly 4,000 patients undergoing TKA or THA who received extended oral antibiotic prophylaxis, researchers found that administering antibiotics for one week after surgery significantly lowered PJI rates at one year, even among those at high risk for infections. The study was presented on Tuesday.

The analysis expanded earlier research of this antibiotic approach in a smaller group of patients who were followed for 90 days. “With this particular study, we wanted to validate our prior work on this protocol in a larger cohort of patients and with greater duration of follow-up,” study author R. Michael Meneghini, MD, FAAOS, told AAOS Now Daily Edition. “One of the criticisms of our initial study and findings was that our PJI rates were recorded during the initial 90-day postoperative period and that additional PJI might occur out to one year, implying that our extended oral antibiotic protocol was ‘kicking the PJI-can down the road.’”

Dr. Meneghini, director of the Indiana University Health Hip and Knee Center, and colleagues examined postoperative PJI rates in a total of 3,862 primary THAs and TKAs performed between 2011 and 2019 at a suburban academic hospital.

The hospital had modern perioperative and infection-prevention protocols but, beginning in 2015, implemented a seven-day oral antibiotic prophylaxis protocol after discharge for patients considered high risk for PJI. For this analysis, patients were categorized into one of three groups:

  • patients not at risk for PJI per protocol and therefore not given extended oral antibiotic treatment (TKA, 594; THA, 488)
  • patients at risk for PJI per protocol but not given extended oral antibiotic treatment because the protocol was not in place (TKA, 561; THA, 309)
  • patients at risk for PJI who received extended oral antibiotic prophylaxis per protocol (TKA, 1,196; THA, 707)

Researchers compared rates of PJI diagnosis within one year postoperatively between patients who did or did not receive the extended antibiotic protocol.

Overall, the rates of PJI within one year were 0.8 percent for TKA and 2.3 percent for THA. Compared with high-risk patients who received extended antibiotics, those who did not were 3.1 times (P = 0.025) and 3.2 times (P = 0.008) more likely to develop PJI after TKA and THA, respectively.

“Giving total hip and knee arthroplasty patients who are at high risk for postoperative PJI a seven-day course of oral antibiotic can mitigate the risk of PJI to a level even lower than observed in low-risk patients,” Dr. Meneghini noted. Infection rates were 0.9 percent for high-risk patients versus 1.3 percent for low-risk patients. The influence of risk factors on infection rates is shown in the Table.

Looking at factors that may predispose patients to postoperative PJI, the researchers found that male sex was a predictor of greater PJI risk specifically for TKA but not THA, irrespective of the study group. “A male patient undergoing a TKA could mitigate his risk of PJI dramatically by taking seven days of oral antibiotic prophylaxis,” Dr. Meneghini said.

“In addition, our data revealed that a one-week supply of extended oral antibiotic is also cost-effective, with a number needed to treat of 57 patients to prevent one PJI,” he added.

The study is limited by its single-center and retrospective design, but Dr. Meneghini said that these results “set the stage for a large, multicenter, randomized, controlled study to evaluate this extended oral antibiotic protocol.”

Dr. Meneghini’s coauthors of “Extended Oral Antibiotics Prevent Periprosthetic Joint Infection in High-risk Cases: 3,862 Patients with 1-year Follow-up” are Michael M. Kheir, MD; Julian E. Dilley, MD; and Mary Ziemba-Davis, BA.

Ariel DeMaio is the managing editor of AAOS Now. She can be reached at