Effect of torsion on microarterial anastomosis patency

All kinds of technical faults must be prevented in microvascular anastomosis for successful reconstructive microsurgery. Torsion at the anastomosis site is one of the most basic technical errors. In this study, we investigate the effect of different degrees of microarterial torsion on patency and its physical changes on anastomosis in a rat model. A total of 144 microanastomosis were performed in 72 Sprague-Dawley rats. They were divided into 9 groups. The anastomosis was performed at 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, 315 degrees, and 360 degrees of torsion randomly. Patency rates and the narrowest point of the artery after the anastomosis were recorded after 1 hour for each group. In the second stage of the study, the 9 groups were divided into 2 groups for patency rates and histopathological sampling at the second and seventh days postoperatively. The femoral arteries in all groups were all patent at the end of 1 hour. Only 5 microanastomosis were thrombosed (one in the 45 degrees group, one in the 225 degrees group, one in the 270 degrees group, and two in the 315 degrees group) at the second day of exploration. Only two arteries were thrombosed (one in the 45 degrees group and one in the 315 degrees group) at the seventh day of exploration. The patency rate was 96.8% in experimental groups excluding the control group. Different degrees of torsion had no statistically significant effect on the patency rates of microvascular anastomosis. Torsional repair of the femoral artery in the rat has no significant histopathologic changes, but alternately, endothelial integrity was affected by excessive degrees of torsion. Different degrees of torsion at the anastomosis site do not affect patency rates and cross sectional histology of rat femoral arteries. In clinical practice, minor torsion can be tolerated, however, factors affecting patency such as tension, diameter disproportion, and tight closure can affect the final result of anastomosis. We observed that torsional force of the vessel is distributed along the artery to the weakest point.