Utilizing Electrochemistry for Infection Prevention and Enhanced Osseointegration in Orthopedic Implants

Orthopedic implant failure is commonly caused by aseptic loosening and infection, accounting for respectively 18% and 20% of failures in total joint replacement. Implant site infections occur when bacteria and other microbes attach to the implant surfaces and form biofilms, leading to implant failure and subsequent removal. On the other hand, aseptic loosening can result from several factors, including implant movement relative to the bone, production of wear particles causing inflammation and bone loss, and inadequate integration between the implant and the patient’s bone. This research focuses on osseointegrated orthopedic prostheses for appendicular skeleton reconstruction which consist of a metallic implant anchored to the remaining bone and connected to an external prosthesis through a transcutaneous connector. Socket-mounted prostheses have traditionally been the standard for recovery and mobility following amputation. Osseointegrated prostheses have emerged as a promising technology, addressing the challenges associated with socket-based prostheses and significantly improving the quality of life for amputees. Nonetheless, the two major challenges that require in-depth investigation in osseointegration are infection prevention and ensuring successful integration between the prosthesis and the residual limb. These two issues are pressing concerns as estimates suggest that the population living with limb loss in the United States alone will reach 3.6 million within three decades, posing a significant challenge for young and active individuals. This master thesis aims to evaluate the potential of electrochemical surface modification techniques to enhance osseointegration and prevent or treat periprosthetic infections in osseointegrated prostheses. One such technique involves creating titanium dioxide (TiO2) nanotubes on the surface of the implant through anodization and loading them with drugs using electrophoretic deposition (EPD) for controlled release. Previous in vitro studies have demonstrated that titanium (Ti) grade 5 ELI (extra low interstitials) K-wires with TiO2 nanotubes loaded with gentamicin and chitosan exhibit superior infection prevention capabilities compared to bare Ti implants when dealing with Staphylococcus aureus infections. Therefore, the objective of this research is to evaluate the efficacy of this electrochemical surface modification technique in vitro to quantify the antibiotic release and prevent cytotoxicity and in vivo using a mouse model of implant associated infection. Finally, an evaluation of the scalability of the anodization process for creating TiO2 nanotubes on Ti grade 5 ELI K-wires with a 12mm diameter is performed. This research contributes to the advancement of osseointegrated prostheses by comprehensively assessing the efficacy of electrochemical surface modification techniques in infection prevention and osteointegration enhancement. The findings have the potential to inform improved prosthetic production steps and significantly enhance the quality of life for individuals with limb loss. Addressing the growing demand for innovative prosthetic solutions, this research is a crucial step towards improving healthcare outcomes for amputees and providing a brighter future for those affected by limb loss.