Intraoperative Bone Perfusion Assessment Using Fluorescence Imaging in a Simulated Fracture Model: Effects of Osteotomy and Periosteal Disruption on Bone Perfusion During Amputation.

Background: Accurate debridement of poorly perfused bone and soft tissue is critical to reduce the risk of infection in open fracture or of recurrent fracture-related infection (FRI). However, accurate delineation of viable and nonviable tissue is difficult with current technology. The aim of this pilot study was to develop and evaluate an indocyanine green (ICG)-based dynamic contrast-enhanced fluorescence imaging (DCE-FI) strategy to provide intraoperative, objective, real-time information on bone perfusion using an osteotomy model in patients undergoing lower-extremity amputation.

Methods: Fifteen patients who were ≥18 years of age and were undergoing lower-extremity amputation were included in this study. Perfusion-related kinetic parameters derived from DCE-FI, including maximum fluorescence intensity, ingress slope, and blood flow, were compared among 3 conditions reflecting sequentially increasing osseous damage: baseline, osteotomy (disruption of endosteal blood flow), and osteotomy plus periosteal stripping (disruption of endosteal and periosteal blood flow).

Results: There were significant decreases in median values from baseline to after osteotomy alone for maximum intensity (96.2 to 58.9 relative fluorescence units [RFUs]), ingress slope (3.2 to 2.0 RFU/second), and blood flow (6.7 to 4.9 mL/min/100 g). Following osteotomy plus periosteal stripping, there were also significant decreases in median values for maximum intensity (12.0 RFU), ingress slope (0.2 RFU/s), and blood flow (0.8 mL/min/100 g). The Mann-Whitney U test confirmed a significant perfusion reduction (p < 0.001) in the tibial diaphysis due to these injuries. The areas under the curve (AUC) in the receiver operating characteristic (ROC) analysis for identifying periosteal stripping (compared with only osteotomy or no osseous damage) were 0.89 to 0.90, which were higher than the AUCs for identifying any osseous damage (osteotomy with or without periosteal stripping) compared with no damage, 0.75 to 0.82.

Conclusions: This clinical study utilizing DCE-FI for intraoperative bone perfusion assessment in orthopaedic surgery demonstrated that kinetic variables derived from DCE-FI can effectively characterize and classify degradation of bone perfusion due to osteotomy and osteotomy plus periosteal stripping.

Level Of Evidence: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.