Dead or alive — use of indocyanine green angiography for intraoperative assessment of bone vitality in nonunion fractures: a controlled case series of four patients

Background. Indocyanine green (ICG) fluorescence imaging is a surgical tool with increasing applications in various surgical disciplines. During nonunion resection, the assessment of bone vascularization is currently based only on the surgeon’s experience. We introduced the use of indocyanine green (ICG) angiography in orthopedics. The aims of the study: 1) to use ICG fluorescence angiography to evaluate the bone perfusion in patients with atrophic nonunion, where poor or absent ICG flow reveals avascular tissue associated with bone necrosis requiring surgical resections; 2) to describe our case series of patients operated with this technique. Methods. We used ICG angiography in patients operated for tibial nonunion resection. We administered 0.5 mg/kg of ICG powder dissolved in sterile saline at 2.5 mg/ml concentration. The time from the injection to the beginning of appreciation of the green dye was measured. Non-viable bone was resected accordingly. Patient underwent routine follow-up. We enrolled all the suitable patients operated from April 2019 to June 2021 and matched three control patients for each of them. We reviewed their medical records and noted any relevant data. Results. We enrolled 4 cases and 12 controls, all male. The mean age was 30.8±6.9 years. The mean duration from trauma to surgery was 10.5 (0.7-25.0) months. The mean duration of surgery was 190.8±40.3 min. The defect size was 4.89±2.03 cm. ICG allowed rapid visualization of bone vascularization after 25-45 sec. No adverse events were observed. The mean external fixation time was 11.8±5.0 months. The mean external fixation index was 2.69±1.10. Seven patients needed a surgical revision during treatment. Three patients underwent reintervention after frame removal. There are no statistically significant differences between cases and controls. Conclusions. The research findings of this study are limited by the small number of observations. However, this technique is safe, easy, and rapid and may contribute to intraoperative decision of how much to resect. Using ICG could objectively demonstrate bone perfusion to help surgeons to avoid massive bone defects.