Silver oxide-containing hydroxyapatite coating has in vivo antibacterial activity in the rat tibia

Bacterial infection is a serious postoperative complication of joint replacement. To prevent infections related to implantation, we have developed a novel antibacterial coating with Ag-containing hydroxyapatite (Ag-HA). In the present study, we examined the antibacterial activity of Ag-HA implant coatings in the medullary cavity of rat tibiae. Forty 10-week-old rats received implantation of Ag-HA- or HA-coated titanium rods, then were inoculated with approximate to 1.0x102 colony-forming units of methicillin-resistant Staphylococcus aureus. Bacterial counts were calculated for rats euthanized at 24, 48, and 72h postoperatively. Serum levels of Ag (in the Ag-HA group only) were calculated for rats euthanized at 24, 48, 72h and 4 weeks. Radiographic evaluations of bone infection were also performed at 4 weeks. Tibiae from both groups showing infection were evaluated histologically. Significant differences in bacterial counts were seen at 24, 48, and 72h. Mean concentrations of Ag in serum peaked about 48h after implantation, then gradually decreased. Mean radiographic scores for infection were significantly lower with Ag-HA implants than with HA implants. Histological examination showed better results for abscesses, bone resorption, and destruction of cortical bone around Ag-HA-coated implants. These results indicate that Ag-HA coatings may help prevent surgical-site infections associated with joint replacement. (c) 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1195-1200, 2013