The mechanical master-slave manipulator: An instrument improving the performance in standardized tasks for endoscopic surgery

Background: This study aimed to evaluate the feasibility and efficacy of a mechanical minimally invasive manipulator for endoscopic surgery. In contrast to currently available motorized master-slave manipulators, this mechanical manipulator consists of two purely mechanical, hand-controlled endoscopic arms with joints that allow seven degrees of freedom (DOF). Methods: For the study, 30 medical students performed four different tasks in a pelvic trainer box using either two conventional endoscopic needleholders or a set of mechanical manipulators. The exercise consisted of four different tasks: repositioning of coins, rope passing, passing of a suture through rings, and tying of a surgical knot. All experiments were recorded on videotape (S-VHS), and the data were analyzed afterwards by an independent observer using a quantitative time-action analysis. Results: A significant difference in the number of total actions (including failures) favoring the mechanical manipulator group was shown in most exercises. A significant difference in failures per task was shown in favor of the mechanical manipulator group as well. There was no significant difference shown in the total time per exercise. Conclusions: The tasks clearly demonstrated the efficacy of the mechanical manipulator, although some technical flaws emerged during the experiments. Considering the fact that a first prototype of the mechanical manipulator was tested, modifications are to be expected in a next model. These experiments show the potential of the mechanical manipulator, and it is expected to be a competitive and economical instrument for endoscopic surgery in the near future.