Analysis of the knot-tying force in dog models

From our experience of endoscopic surgery using the surgical robot da Vinci at our hospital, it has become clear that the lack of a sense of touch of the forceps makes meticulous operations difficult. For the development of a surgical robot that would impart a sense of touch, we investigated the appropriate knot-tying force by determining the relation between this force and wound healing in dog models. We cut and then sutured the jejenum of Beagle dogs, using a series of knot-tying forces (0.5-5.0 N). The jejenum was then removed on the 4^th, 7^th, 11^th and 14^th postoperative days, and the microvessel density for each force was measured to determine the appropriate knot-tying force for the jejenum. The microvessel density in the submucosa on the 7^th and 11^th postoperative days was significantly higher for the knot-tying force of 1.5 N than for other forces used. Thus, the results of our study suggested that a knot-tying force of 1.5 N was the most appropriate force for suturing of wounds of the jejenum. We consider that this result would be useful for the development of a surgical robot that imparts a sense of touch to the surgeon´s hand.