RESUMO
The objective of this study was to estimate the tensile strength of surgical knots made using the da Vinci robot. Four different types of flat square knots (strand-to-strand 4 throw, strand-to-strand 6 throw, loop-to-strand 4 throw, and loop-to-strand 6 throw) were made using the da Vinci-S system by 4 different surgeons, all experienced with the system. For the knots, we used braided polyglactin 910 (Vicryl 2-0). Hand-tied, flat, square, 4-throw strand-to-strand knots were used as reference. The tensile strength was measured for all knots using the Instron 5566 system calibrated to an accuracy of + or - .5% at 4 to 10 newtons (N) and + or - .4% at greater than 10 N. Compared with reference knots, only 1 of 4 surgeons could make knots as equally strong with the robot. For all surgeons, strand-to-strand knots had a significantly higher tensile strength than loop-to-strand knots when made with the robot. Adding 2 throws to the knot did not increase the knots strength in the robot. It is possible to make equally strong surgical knots with the da Vinci robot as by hand; however, despite previous experience with the robot, only 1 of 4 surgeons managed to do so. Adding 2 throws to R4SS and R4LS knots did not increase the tensile strength significantly for any of the 4 surgeons. It is important to train and tie knots using the da Vinci system with the same care as by hand and to be aware of possible differences in knot-tying technique with the robot and manually. With the robot, strand-to-strand knots were stronger than loop-to-strand knots, and should be preferred.
