Antibacterial iodine-supported titanium implants

Deep infection remains a serious complication in orthopedic implant surgery. In order to reduce the incidence of implant-associated infections, several biomaterial surface treatments have been proposed. This study focused on evaluating the antibacterial activity of iodine-supported titanium (Ti–I2) and its impact on post-implant infection, as well as determining the potential suitability of Ti–I2 as a biomaterial. External fixation pins were used in this experiment as trial implants because of the ease of making the septic models. The antibacterial activity of the metal was measured using a modification of the Japanese Industrial Standards method. Activity was evaluated by exposing the implants to Staphylococcus aureus or Escherichia coli and comparing reaction of pathogens to Ti–I2 vs. stainless steel and titanium controls. Ti–I2 clearly inhibited bacterial colonization more than the control metals. In addition, cytocompatibility was assessed by counting the number of colonies that formed on the metals. The three metals showed the same amount of fibroblast colony formation. Japanese white rabbits were used as an in vivo model. Three pins were inserted into both femora of six rabbits for histological analysis. Pin sites were inspected and graded for infection and inflammation. Fewer signs of infection and inflammatory changes were observed in conjunction with the Ti–I2 pins. Furthermore, osteoconductivity of the implant was evaluated with osteoid formation surface of the pin. Consecutive bone formation was observed around the Ti–I2 and titanium pins, while little osteoid formation was found around the stainless steel pins. These findings suggest that Ti–I2 has antimicrobial activity and exhibits cytocompatibility. Therefore, Ti–I2 substantially reduces the incidence of implant infection and shows particular promise as a biomaterial.