In-vivo imaging of the sentinel vein using the near-infrared vascular imaging system in hallux valgus patients.

Background: A high incidence of dorsomedial cutaneous nerve (DMCN) damage in hallux valgus surgery has been reported. Identification of the vein around 1st metatarsal head is reported to be helpful to reduce the DMCN damage during surgery. The near-infrared (NIR) vascular imaging system, the VeinViewer Flex, projects the vein onto the skin. The purpose of this study was to investigate the difference of the vein course between normal and hallux valgus foot using the VeinViewer Flex, and to validate that the DMCN was accompanied with its vein.

Methods: Twenty-seven feet with the hallux valgus and 27 feet in healthy subjects were included. The vein was projected onto the skin at the metatarsal head by the VeinViewer Flex. The distance between the vein and the mid-line of the metatarsal head was measured. The correlation of the distance and hallux valgus angle or 1-2 intermetatarsal angle (IMA) was analyzed. The vein depicted by the VeinViewer Flex and operative findings was compared in 4 patients during surgery.

Results: The vein in the hallux valgus patients shifted toward the dorsolateral side on the metatarsal bone head compared to that in healthy subjects. The distance from the midline of the 1st metatarsal bone to the vein in the hallux valgus (12.1 mm) was significantly higher than that in healthy subjects (2.7 mm) (p < 0.05). There was a significant correlation between the shift of the vein course toward dorsolateral and IMA. Surgical exploration revealed that the vein depicted by VeinViewer Flex could be easily identified and the nerve was along with this vein in all 4 surgical cases.

Conclusions: The vein in the hallux valgus patients shifted toward the dorsolateral on the metatarsal bone and it could be a landmark to identify DMCN. The NIR vascular imaging system would be useful to reduce the risk of nerve damage in great toe surgery.