The effects of physical constraints in laparoscopic surgery.

In order to provide guidelines for the development and evaluation of advanced laparoscopic instrumentation (including teleoperated devices), we assessed the impact of constrained motion on surgeons' ability to perform standardized pick-and-place and suturing tasks when using an emulation of a perfectly transparent teleoperator under direct, binocular vision. The surgeons' performance when using the emulator represents an upper bound on performance using any conceivable teleoperator with one-to-one force and motion scaling. Our analysis examines the mean differences in task completion time between three open tool configurations and two laparoscopic tool configurations with various degrees of freedom (DOFs). Fifteen laparoscopic surgeons participated in the study. We show that avoiding reversed hand and tool motions and adding DOFs significantly improves suturing performance. In the pick-and-place task, avoiding the reversed motions also improves performance, but adding DOFs to an open tool configuration does not. For both tasks, subjects who use open tools constrained to four DOF complete their tasks in approximately 38% less time than when using standard four-DOF laparoscopic tools. The marginal benefit to overall surgical time of adding two additional degrees of freedom is likely to be small (approximately 2%), although surgeons may then feel confident in attempting more difficult procedures.