SAN FRANCISCO — Routinely giving antibiotic prophylaxis for 10 days in arthroplasty patients apparently did nothing beyond what was achieved with shorter protocols to prevent prosthetic joint infections (PJIs) at one major medical center.

PJI rates at Vanderbilt University Medical Center in Nashville were no lower after a policy was implemented in 2020 to provide extended oral antibiotics to all patients undergoing total hip or knee replacement, according to Vanderbilt’s J. Ryan Martin, MD, speaking here at the American Academy of Orthopaedic Surgeons annual meeting.

Among a total of about 4,600 knee and hip replacement procedures done from 2018 to 2022, patients receiving extended oral antibiotics experienced PJIs within 90 days at a rate of 0.96%, versus 0.82% of patients only receiving perioperative antibiotics, Martin reported.

One-year PJI rates also showed no real difference: 0.96% with extended oral antibiotics (i.e., no new infections were seen after 90 days) as compared with 1% of patients who didn’t receive extended oral antibiotics.

Consequently, Martin said, “we cannot recommend widespread adoption” of extended oral antibiotics for preventing PJIs after arthroplasty.

Vanderbilt’s move in 2020 to provide extended oral antibiotics routinely in joint replacements — echoed at many other centers — was prompted by a retrospective study appearing in late 2018. It showed that extended oral antibiotics had cut rates of PJIs by 75% to 80% in high-risk patients. With such a reduction in this important complication of arthroplasty, which often leads to revision, many clinicians felt that continuing with standard perioperative prophylaxis would be unethical. After looking at this and other studies, Vanderbilt decided to make a 10-day postoperative regimen of oral antibiotics the standard of care. (Other extended oral antibiotic protocols have set the period at 7 days.)

Yet the extended treatment is not without potential harms, Martin noted. It might promote development of antibiotic resistance, and some patients experience direct adverse effects from the drugs.

The new study alleviated the former concern. Only two of some 1,800 patients receiving extended oral antibiotics at Vanderbilt showed antibiotic resistance, versus five of about 2,800 given standard perioperative antibiotics.

Martin’s group did find a hint of benefit from extended oral antibiotics among patients considered to be at high risk for PJIs, who were about half of the entire cohort. In this subgroup, 90-day and 1-year PJI rates were considerably higher in the group who didn’t receive extended oral antibiotics: 2.3% and 2.6%, respectively, versus 0.8% with extended oral antibiotics. But neither difference reached statistical significance.

Asked during the audience Q&A whether Martin saw any role for extended oral antibiotics in arthroplasty, he replied, “I still think there may be some,” such as patients with expected PJI risk of 4% or more.

He told MedPage Today that Vanderbilt hasn’t yet formally abandoned the all-comers policy for extended oral antibiotics. “It’s being debated now,” he said, adding that the institution is collaborating in a prospective randomized study developed by the Mayo Clinic to settle the issue.

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