Bone flap perfusion assessment using near-infrared fluorescence imaging

Abstract Background Microsurgical vascularized bone flaps are a versatile technique for reconstructing large bone defects. However, the assessment of perfusion is challenging, because clinical examination is difficult intraoperatively and often not possible postoperatively. Therefore, it is important to develop techniques to assess the perfusion of vascularized bone flaps and potentially improve the surgical outcomes. Near-infrared (NIR) fluorescence imaging has previously been shown to provide real-time, intraoperative evaluation of vascular perfusion. The present pilot study investigated the ability of NIR imaging to assess the perfusion of vascularized bone flaps. Methods Vascularized bone flaps were created in female Yorkshire pigs using well-established models for porcine forelimb osteomyocutaneous flap allotransplantation ( n = 8) and hindlimb fibula flaps ( n = 8). Imaging of the bone flaps was performed during harvest using the FLARE intraoperative fluorescence imaging system after systemic injection of indocyanine green. Perfusion was also assessed using the standard of care by clinical observation and Doppler ultrasonography. NIR fluorescence perfusion assessment was confirmed by intermittent clamping of the vascular pedicle. Results NIR fluorescence imaging could identify bone perfusion at the cut end of the osteotomy site. When the vascular pedicle was clamped or ligated, NIR imaging demonstrated no fluorescence when injected with indocyanine green. With clamp removal, the osteotomy site emitted fluorescence, indicating bone perfusion. The results using fluorescence imaging showed 100% agreement with the clinical observation and Doppler findings. Conclusions Vascularized bone transfers have become an important tool in reconstructive surgery; however, no established techniques are available to adequately assess perfusion. The results of our pilot study have indicated that NIR imaging can provide real-time, intraoperative assessment of bone perfusion.