Development of hydrofluoric acid-cleaned silicon nitride implants for periprosthetic infection eradication and bone regeneration enhancement

Highlights: • Si₃N_4AC with HF cleaning increased the roughness and wettability of Si₃N₄ surface. • HF cleaning improved biocompatibility and bacterial resistance of Si₃N₄. • A reliable rat tibial osteomyelitis model was built for Si₃N_4AC evaluation. • Si₃N_4AC could be used for implant-associated osteomyelitis control. Orthopedic implant is commonly associated with occurrence or relapse of osteomyelitis. This study developed a hydrofluoric acid (HF) cleaned silicon nitride (Si₃N₄) implant Si₃N_4AC for osteomyelitis control and established a rat tibial osteomyelitis model to evaluate its efficacy on eradicating periprosthetic infection and enhancing bone regeneration. In vitro studies revealed Si₃N_4AC had improved biocompatibility and inhibited Staphylococcus aureus adhesion. A custom-made Si₃N_4AC implant was prepared and inserted into the rat tibia longitudinal cavity inoculated with Staphylococcus aureus. The in vivo bacteriostatic and osteogenic efficacies of Si₃N_4AC implant were evaluated by histological, microbiological and Micro-CT analyses and compared with implants of pure Ti and Si₃N₄ . Si₃N_4AC implant group revealed 99.5% inhibition of periprosthetic Staphylococcus aureus compared to the osteomyelitis group after 14 days post-operation. Implant-adhering bacteria density of Si₃N_4AC was also much lower than pure Ti and Si₃N₄. In addition, micro-CT evaluation of peri-implant bone formation under the condition of periprosthetic osteomyelitis after 30 days post-surgery confirmed the osteogenic ability of Si₃N_4AC. Taken together, Si₃N_4AC can be an effective orthopedic biomaterial to eradicate periprosthetic infection and enhance bone regeneration.