A Pilot Study to Evaluate Single Dose Indocyanine Green 24 Hours Prior to Operative Treatment of Orthopaedic Infection

Infection following trauma is one of the most prevalent and challenging complications faced by orthopedic surgeons in both military and civilian populations, occurring after up to 60% of open bone fractures. Several factors specific to this trauma place patients at high risk for infectious complications, including: traumatized tissues, open contaminated fracture, soft tissue coverage issues, catabolic state due to poly-trauma, prolonged hospitalization with exposure to nosocomial bacteria, and presence of metallic implants8. Infection requires one or more unplanned surgical procedures and leads to prolonged morbidity, loss of function, and potential loss of limb. Failed treatment for bone infection results in recurrent infection, requiring repeat surgical procedures in approximately 30% of patients.

Infection is known to display the enhanced permeability and retention effect with increased vascular permeability. Second window or 24h ICG represents an ideal method to identify these areas of increased vascular permeability. In some instances infected tissue can be hard to distinguish from healthy tissue when ICG is given immediately before optical imaging Second window ICG will allow surgeons to better distinguish infected tissue from healthy tissue as the ICG will have a better opportunity to permeate the infected tissue while it will have been expelled from the health tissue.

There are currently no accepted intraoperative tools that can be used to make objective decisions about which bone and tissue is infected and which is normal. Methods currently used to guide debridement are quite rudimentary. Clinical judgment is based on the gross appearance of soft tissue and bone, including color, turgor, and extent of soft tissue stripping. A burr may be used to look for bleeding bone. More extensive debridement is thought to minimize risk of index infection or reduce the rate of persistent infection; however, this comes at the cost of increasingly complex reconstructive procedures to fill bony defects. Clearly what is needed is a functional imaging system which can identify infected tissues to guide surgeons in the amount of tissue to debride. In turn, this will lead to fewer infections and a more effective treatment of SSIs at the fracture site. Both scenarios will allow patients to return to duty or work sooner.

The study endpoint is to determine the variability of bone and soft tissue perfusion in infection patients when given a single dose of ICG 24h prior to surgical debridement. The long term goal of this study is to aid in the development and optimization of bone specific imaging strategies that can be used to guide debridement and to optimize the quality of bone / tissue resection to minimize complications.