Antibacterial Electrophoretically Loaded Titania Nanotubes on Titanium Alloy Implants Enhance Osseointegration

Primary hip and knee arthroplasties are common surgeries in the U.S., with periprosthetic joint infection (PJI) being the leading cause of implant revision. Systemic antibiotics often fail to achieve sufficient local concentrations, driving interest in localized drug delivery. Titanium (Ti) implants modified with titania nanotubes (TNTs) provide an increased surface area for drug loading and controlled release. Previous studies have shown that gentamicin-loaded TNTs inhibit Staphylococcus aureus growth in vitro without compromising osteoblast viability. This study investigated the effect of gentamicin-chitosan (GC)-coated TNT implants in a murine model, hypothesizing a positive impact on osseointegration. Titanium alloy (Ti6Al4V) wires were anodized to form TNTs and then coated with gentamicin-chitosan (GC) via electrophoretic deposition. Implants (Bare, TNT, TNT+GC; n = 30) were inserted bilaterally into femoral canals of C57BL/6J mice. After > 1 month, osseointegration was assessed by histological point counting, scanning electron microscopy (SEM)-based areal analysis, and mechanical pull-out testing. ANOVA was used to identify differences between groups, and linear regression was applied to account for harvest time, bone contact area, and anatomical section. Bone area fraction (BAF) around the implant measured by the SEM-areal method was significantly higher around TNT+GC (18.4% ± 1.1) and TNT (16.5% ± 1.4) versus Bare (9.0% ± 2.3) (p < 0.0028) implants. The maximum fixation strength was higher for TNT (0.878 ± 0.175 N/mm²) and TNT+GC (0.853 ± 0.215N/mm²) when compared to bare implants 0.316 ± 0.082 N/mm²) (p = 0.048 and p = 0.050, respectively). No significant differences appeared between TNT and TNT+GC. These findings indicate that GC coatings on TNT implants do not impair osseointegration and may even enhance bone-implant integration. Such coatings may therefore provide dual benefits, offering antibacterial protection while improving bone fixation, making them a promising strategy for PJI prevention. Further long-term studies are needed to confirm durability and clinical translation.