Safe Insertion Angle of the Suture Button to Avoid Saphenous Structure in Syndesmosis Injury

In placing the medial suture button for syndesmosis injury, the risk of great saphenous vein and saphenous nerve injury has been reported. This study aimed to determine the safe insertion angle of the guide pin to avoid saphenous structure injury during suture button fixation. The incidence of saphenous structure injury was investigated using 8 legs of cadavers. The greater saphenous vein was depicted on the skin using near-infrared light (VeinViewer^® Flex) and the distance between the greater saphenous vein and the posterior edge of the tibia at levels of 10, 20, and 30 mm from the joint line of the tibiotalar joint was measured in the 60 legs of healthy participants. On computed tomography (CT) images, the angles between the greater saphenous vein and transmalleolar axis at levels of 10, 20, and 30 mm from the joint line of the tibiotalar joint were measured. The cadaveric study revealed that the percentages of contact with the saphenous nerve were 8.3% to 16.7%. Using near-infrared light, the vein and tibia distance was 32.9 ± 6.8 mm of 10 mm, 26.6 ± 6.4 mm of 20 mm, and 20.4 ± 6.4 mm of 30 mm. The angle between the vein and transmalleolar axis was 1.0° to 9.4°, and more proximal, the angle was smaller. The veins depicted by near-infrared light can be a landmark to identify great saphenous vein, and injury of the saphenous structure can be prevented using VeinViewer Flex or considering the insertion angle defined in this study when placing the suture button for syndesmosis injuries.Level of Evidence: Level IV.