Assessing periimplant tissue infection prevention in a percutaneous model

Prevention of infection remains a challenge to the implementation of the percutaneous sseointegrated implant technology of prosthetic limb attachment in amputees. The purpose of this investigation was to determine if a broad spectrum antimicrobial, Ceragenins™ (CSA - 13), could prevent pin track infections in a percutaneous pin wound site in a sheep model. The pin was inserted through both cortices of the proximal tibia and protruded through the skin on the medial side of the hind leg. All twenty sheep received the smooth titanium alloy pin. Ten sheep were treated with a polyurethane foam pad coated with a CSA-13-polyurethane polymer conjugate, and ten sheep served as controls receiving an uncoated, sterile foam pad. The sheep were euthanized at the end of the 24-week trial or when they presented with clinical signs of pin track infection. After euthanasia, cultures were obtained of muscle, blood, and bone, and muscle and bone were harvested for histology. In addition to the clinical signs of infection, the sheep was considered infected if at least one tissue culture was positive and/or one histologically stained sample was found positive. Statistical analysis included Kaplan-Meier survivorship curves to display time to pin track infection rates and the Wilcoxon-Mann-Whitney test to compare the Appositional Bone Index between the groups.