Gut bacteria linked to successful joint replacement

Having healthy gut flora could lower the risk of infection following knee and hip replacement surgeries, while an unhealthy intestinal flora may increase the risk of infection, according to a new study by researchers from Cornell University published in the Clinical Orthopaedics and Related Research.

In the study, the researchers led by Christopher Hernandez, PhD, the study’s first author, used mice fitted with tiny artificial knees developed by co-authors Alberto Carli, MD, and Mathias Bostrom, MD. The mouse knee replacement was originally developed to improve implant design and to study how bone grows into these implants. Carli then advanced the model to study infections.

In normal mice, immune system markers in the bloodstream rise during an infection, as the body responds. But in the study, these markers did not rise in mice with unhealthy microbiomes that also developed infections. The results suggest that mice with unhealthy microbiomes may have compromised immune systems.

To prevent infection, surgeons take multiple precautions during surgery. As a result, infections following joint replacement surgeries are rare, affecting only 1 percent of patients who have procedures. However, infections are the number one reason for replacing an artificial knee and the third leading cause for replacing an artificial hip.  

Over 1 million Americans opt for a knee or hip replacement each year. Infection of an artificial hip or knee is a rare, but debilitating complication, researchers said.

In the future, the researchers said they will investigate whether patients could be prepped ahead of surgery with emerging microbiome-based therapies or a readily available one, such as a regimen of probiotics.

"This research is in early stages,” Hernandez said in a statement, “but if it pans out in humans, it's possible we could change or fix the patient's gut microbiome before they go in for hip or knee replacement and that could further reduce the risk of infection."