Assessing peri-implant tissue infection prevention in a percutaneous model

Infection remains the main challenge to percutaneous, intramedullary osseointegrated implant technology. The purpose of this investigation was to determine if a broad spectrum antimicrobial, Ceragenin (CSA-13) could prevent pin track infections in a percutaneous tibial pin site in a sheep model.

In 20 sheep, a smooth titanium alloy pin/implant was inserted percutaneously through the medial skin and both cortices of the proximal tibia. In 10 sheep, the pin/skin interface was treated with a CSA-13-embedded foam pad. Ten sheep served as controls receiving an untreated pad. At the end of 24 weeks, or if they presented with clinical signs of infection, the animals were euthanized. Histological stains were processed from soft tissue and bone, and bacterial cultures were taken from tissue, bone, and blood. In addition to clinical signs, sheep were considered infected if at least one tissue culture and/or histologically stained sample was positive.

Compared with the controls, CSA-13 did not prevent pin track infection (p = 0.88). Large gaps around the pin indicated a lack of skin-pin adhesion.

In this application, CSA-13 was not effective in preventing pin track infections. This study suggests that maintaining skin attachment, at the implant surface of osseointegrated implants, is essential as a primary barrier to infection. Local antimicrobial treatments should be considered a secondary barrier to bacterial invasion of the pin/skin interface and deeper tissues.