Tiny Antibiotic Beads Fight Infections after Joint Replacement Surgery

    More than 1 million people undergo total joint replacements each year, and nearly 10,000 will develop infections. To reduce this infection risk, an orthopaedic surgeon from Houston Methodist has created small antibiotic beads that are implanted with the new joint to slowly release medicine for several weeks.

    Terry Clyburn, MD, has developed antibiotic microspheres that are as small as grains of salt and that are designed to release antibiotics at a level high enough to eradicate infectious organisms for 3 to 6 weeks – the time frame when an infection is most likely to develop.

    “There is a risk of infection with any surgery, but infections after a joint replacement surgery are harder to treat,” Dr. Clyburn said. “The implants are not connected to the body’s bloodstream, so the white blood cells sent to fight the infection cannot reach the implant and kill the bacteria.”

    Currently, most joint replacement patients will be given intravenous antibiotics before and after surgery to help stave off an infection. By coating the implant in the antibiotic microspheres before placing it in the patient’s joint (Figure 1), the antibiotics are delivered directly to the surgical site to help prevent bacteria from developing into an infection.

    Figure 1. A hip replacement implant is coated in antibiotic microspheres developed by orthopaedic surgeon Terry Clyburn, MD. Photo credit: Houston Methodist

    “Most products labeled as time-release will release all of their medication as soon as the protective outer layer is dissolved,” Dr. Clyburn said. “But these microspheres are truly time-release as they have several layers of antibiotics that slowly dissolve and release the medication on the implant and surrounding tissues. Within 6 weeks, the microspheres are completely dissolved and leave nothing behind in the joint that could lead to future problems for the patient.”

    In studies to determine the efficacy of the microspheres, Dr. Clyburn and his team contaminated 2 metal implants with Staphylococcus aureus bacteria and coated 1 with the microspheres before inserting them in animal models. No infections developed in the model that coated with the microspheres.

    “If an infection does develop after a joint replacement surgery, many patients may require surgery to thoroughly clean around the implant or even replace it,” Dr. Clyburn said. “That’s why I’ve been working for more than 15 years to develop these microspheres – to help protect my patients and reduce their risk for major complications after surgery.”

    Dr. Clyburn developed the microspheres in collaboration with Rice University’s Antonios Mikos, PhD, and Catherine Ambrose, PhD, from UTHealth. He is currently seeking approval of the antibiotic microspheres by the Food and Drug Administration and estimates they will be in use in 3 to 8 years.