Silver Ion-Doped Calcium Phosphate-Based Bone-Graft Substitute Eliminates Chronic Osteomyelitis: An Experimental Study in Animals

Abstract

Despite the latest technologies and advances in microbiology and orthopedic surgery, chronic osteomyelitis is still a challenging disorder. Antibiotic resistance and bacterially induced bone destruction can have very serious consequences. We hypothesized that calcium phosphate-based bone graft substitution with silver ion doping would simultaneously treat bone infection and the bony defect in the chronic osteomyelitis. An unicortical 10-mm-diameter bone was harvested in the proximal tibial metaphysis of 24 rabbits. After contaminating the wounds with an infective dose of methicillin-resistant Staphylococcus aureus (MRSA), osteomyelitis was proven radiographically and microbiologically in all rabbits. Animals were than divided into three groups. The first group received vancomycin-impregnated bone cement beads (comparative control group), the second/experimental group received silver ion-doped calcium phosphate beads and the third group received pure calcium phosphate beads (negative controls). Radiographs, intraosseous cultures, and histopathological examinations were performed on postoperative Week 10. The cultures showed no evidence of intramedullary infection in the silver ion-doped calcium phosphate beads group, but they were positive for MRSA in four of the six rabbits in the vancomycin- impregnated bone cement beads group and in all of the eight rabbits in the pure calcium phosphate beads group. Quantitative assessment of histopathological examination showed lowest total damage score in silver ion-doped calcium phosphate beads group (p < .001). Percentage of osteoid tissue + bony tissue was also higher in this group compared with other groups. In the final radiological examinations, it was observed that the changes caused by osteomyelitis in the bone tissue in the silver ion-doped calcium phosphate beads group were much improved compared with the vancomycin-impregnated bone cement beads group. Silver ion doped calcium phosphate-based bone-graft substitute offer the ability to stimulate bone growth, combat infection, and, ultimately, treat experimental chronic osteomyelitis in an animal model.