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Healthy Gut Flora May Lower Risk of Infection Following Joint Replacement Surgery

Knee and hip replacement patients who have healthier intestinal microflora may have a lower risk of developing dangerous periprosthetic joint infections than patients with unhealthy guts.

A patient’s intestinal health may impact their risk of developing infection following hip or knee replacement surgery, according to a new study led by investigators from Cornell's College of Engineering and the Hospital for Special Surgery.

Although surgeons take precautions to prevent infection following joint replacements, the American Academy of Orthopaedic Surgeons notes that about 1 in 100 patients who have hip or knee replacements go on to develop an infection after surgery. Now, a study recently published in the journal Clinical Orthopaedics and Related Research indicates that healthy gut flora may be linked to a lower risk of infection following joint replacement, while unhealthy gut flora may raise the risk of infection.

In an interview with Contagion®, study co-author Christopher J. Hernandez, MS, PhD, explained that an infected joint replacement presents as pain that can prevent the patient from walking. “Treating a periprosthetic joint infection is extremely difficult. At the bare minimum it requires another surgery to clean the infected implant,” he said, adding that a more established infection can require 2 surgeries—1 to put a temporary implant in, and another one 6 weeks later to put a new sterile implant in—and antibiotic dosing.

“Existing interventions for periprosthetic joint infection have poor success rates and some patients develop a second infection and require additional surgeries,” Hernandez continued. “Periprosthetic joint infection is also correlated with increased mortality in the following 5 years.”

In the recent study, the research team used a mouse model to investigate whether the state of the gut microbiota before surgery influences the likelihood of developing an established infection, and how gut health impacts the response to infection. Mice in the study received titanium tibial implants, mimicking a knee replacement to study how bone grows into artificial joints.

To study infections, investigators used 40 mice with gut microbiomes modified with oral neomycin and ampicillin, and 42 untreated mice. They found that although immune system markers in the bloodstream rose during infection in the untreated mice, those markers did not rise in the mice with unhealthy gut flora that developed infections. The study authors say that a similar link between gut health and periprosthetic joint infection has been observed in humans, whereby changing a patient’s gut microbiome before surgery may help lower the risk of infection.

“Although we don’t know exactly how to ‘fix’ a poor gut microbiome, there are interventions that may be beneficial to the host including prebiotics that promote the growth of beneficial organisms, probiotics, or even beneficial microbial metabolites,” said Hernandez. “Many candidate treatments have been identified, but we don’t necessarily know specifically how they would influence periprosthetic joint infection, which ones are best, or what kind of dosing strategy someone could use.”

For now, Hernandez says that there is no clinical data available to suggest a course of treatment for patients to improve or repair the gut microbiome. “At this point the only responsible suggestion I could make would be to follow guidelines from the American Academy of Orthopaedic Surgeons regarding nutritional status of patients prior to total joint replacement."