Extra antibiotics show no infection benefit after joint replacement

A Yale University study found that giving some hip and knee replacement patients an extra week of oral antibiotics after discharge did not significantly cut their risk of joint infection. The finding matters because many orthopedic surgeons use extended antibiotics for patients considered at higher risk, while public health officials warn that unnecessary antibiotic use can drive resistance.

The study, published in The Journal of Arthroplasty, reviewed adult patients who had primary total joint replacement surgery between 2015 and 2025, according to Yale University. The research team reported that infection rates were nearly the same at 90 days and at one year among patients who received extended oral antibiotics and those who did not.

Periprosthetic joint infection is one of the major reasons hip and knee replacements fail, Yale said. Such infections can lead to more surgery, longer hospital stays, and financial and emotional strain for patients.

Surgeons often reserve extended oral antibiotics for patients with risk factors such as diabetes, chronic kidney disease or tobacco-use history, Yale said. The Yale researchers said the added medication did not show a measurable advantage even when they focused on the patients at highest risk.

How the researchers compared patients

Daniel Wiznia, a Yale associate professor who specializes in hip and knee reconstruction and served as principal investigator, said the results challenge a common assumption in medicine that more antibiotic coverage offers more protection. He said the findings should push clinicians to reconsider routine protocols if an added week of medication does not change infection rates.

Because sicker patients are more likely to receive extended antibiotics, the team used propensity matching, Yale said. That method paired each patient who received the added antibiotics with four similar patients who did not, balancing the groups by age, biological sex and overall health status.

The same pattern held among patients with morbid obesity, a condition Yale said raises the risk of surgical complications. According to Wiznia, the study runs counter to several earlier smaller studies that suggested extended antibiotics could help high-risk patients in a cost-effective way.

Ilda Molloy, a co-author of the paper and Yale orthopedic surgeon, said prosthetic joint infection prevention at Yale New Haven Health System involves orthopedic surgery, infectious diseases, microbiology, pharmacy, nursing and other clinical teams. She said the findings support coordinated protocols that address infection risk before, during and after surgery while using antibiotics responsibly.

Yale said standard care at the study site includes nasal screening, antiseptic skin wipes and carefully timed intravenous antibiotics around the time of incision. Wiznia said those immediate infection-prevention steps appear to be the main line of protection, with later oral antibiotics offering diminishing returns.

Antibiotic risks remain a concern

The study did not find a statistically significant increase in immediate complications from extended antibiotics, such as severe allergic reactions or kidney damage, Yale said. Still, the U.S. Centers for Disease Control and Prevention has warned that overprescribing antibiotics can contribute to antibiotic resistance and disrupt healthy gut bacteria.

Wiznia said earlier projections estimated that giving extended antibiotics nationwide to all high-risk joint replacement patients could add 50,000 cumulative years of antibiotic exposure each year. He said such exposure could raise the risk of opportunistic infections including Clostridioides difficile, a painful bacterial infection of the colon.

The researchers cautioned that their study was retrospective, meaning it depended on existing records. Yale said that approach can be limited by missing administrative codes or uncertainty about whether patients took pills at home as prescribed.

Wiznia said randomized trials will be needed for more conclusive evidence. He said prescribing should become more precise, with clinicians considering factors such as blood sugar control or nutrition rather than relying only on broad high-risk labels.

This story draws on original reporting from Medical Xpress.