Biofilm-inhibiting and osseointegration-promoting orthopedic implants with novel nanocoatings

Abstract

Orthopedic implants are medical devices surgically placed into the body to replace a missing joint or bone or to reinforce a damaged structure. However, there is up to a 28% loosening rate on cementless implanted knee joint prostheses within a 4-10-year period after implant insertion, and a 2-5% infection rate for orthopedic implants (joint prostheses and fracture fixation devices). In the USA, total hip and knee arthroplasties currently account for over one million interventions each year. Due to the enormous size of the patient population with orthopedic implants, even a currently low risk of infection or failure has not only caused many patients to suffer, but it has also incurred huge costs for the associated health care system. Therefore, there is an urgent need to develop a novel dual-functional nanocoating technology with judiciously engineered physicochemical properties to address simultaneously the two critical issues long facing orthopedic implants: lack of integration with bone tissue and biofilm-caused infections for the enhanced success of implants. We have generated a nanocoating showing a very promising capability of inhibiting biofilm formation by Staphylococcus aureus and Staphylococcus epidermidis, two of the most common biofilm formers on orthopedic implants, and enhancing bone conductivity simultaneously. The dual-functional nanocoatings coming out of our research demonstrated the following unique features for orthopedic implants: (1) inhibit bacterial colonization and concomitantly promote osteoblast functions; (2) generate long-lasting functionalities for practical clinical applications because these nanocoatings are dense and highly cross-linked without substances of low molecular weight; (3) provide needed abrasion resistance for orthopedic implants and ensure strong coating adhesion to the surface; and (4) improve bone integration and reduce device-related infections in the long run.