A group at Duke University engineered an antibiotic delivery system to make the surfaces of orthopedic implants resistant to bacterial infiltration. The technique involves spraying or painting a combination of hydrophilic and hydrophobic polymers, mixed with an antibiotic of choice, onto the surface of the implant. A UV light is then used to cure the coating in place. The coating then releases the antibiotic over a period of 2-3 weeks, helping to reduce the chance of infection.
Existing orthopedic implants are at risk of infection, resulting in patient morbidity and revision surgeries. The metal surface of most implants provides an ideal place for microbial growth, with little blood flow to carry antibiotics to the site. For vulnerable patients, this can be a serious issue. For instance, pediatric patients with bone cancer often require bone removal and implant placement, but their chemotherapy regimen is typically immunosuppressive, putting them at serious risk of implant infection.
“These kids face the choice of having chemotherapy versus saving their limb or even sometimes needing amputations to survive, which sounds horrific to me,” said Tatiana Segura, a researcher involved in the study. “All they really need is something to rub on the implant to stop an infection from taking hold, because preventing an infection is much easier than treating one. So, we came up with this coating technology that we hope will provide a solution.”
The system consists of a mix of hydrophilic and hydrophobic polymers. A clinician can mix an antibiotic of their choice with the polymers and then apply it to the implant shortly before surgery, using a UV light to initiate a chemical reaction that immobilizes the drug on the implant surface. The antibiotic can be chosen based on the area being treated, or based on knowledge of the microbes present. The mixture can be applied through spraying, painting, or dipping, and so the system is very flexible.
“Our coating can be personalizable because it can use almost any antibiotic,” said Segura. “The antibiotic can be chosen by the physician based on where in the body the device is being implanted and what pathogens are common in whatever part of the world the surgery is taking place.”
Interestingly, the new approach has been trialed in mice, demonstrating a 100% reduction in the incidence of implant-related infections.
“We’ve shown that a point-of-care, antibiotic-releasing coating protects implants from bacterial challenge, and can be quickly and safely applied in the operating room without the need to modify existing implants,” said Christopher Hart, another research involved in the study.
Study in Nature Communications: Point-of-care antimicrobial coating protects orthopaedic implants from bacterial challenge