Design and Evaluation of Haptic Constraints for Laparoscopic Instrument Handling.

Learning and mastering laparoscopic skills is an involved and complicated process, especially in the case of pediatric surgery due to extremely fragile tissues and small spaces. Given these constraints, precise, controlled, and gentle laparoscopic tool motions are essential. Proper handling and ergonomics of laparoscopic tool handling are often overlooked when training novice surgeons. Novice surgeons tend to overgrip the tool, which may lead to applying excessive amounts of force and potential surgical complications. We have developed two constraint mechanisms to enable proper tool handling: one mechanism is a passive kinematic constraint which physically prevents the user from over-gripping the tool. The second mechanism operates under dynamic resistive control. An elastic silicone membrane, secured by a hard plastic clip to the finger loop of the laparoscopic tool, actively resists the user's overgrip. These constraint devices were tested in a series of human subject studies with novice learners. The resulting data shows a both a significant reduction in over-grip and overall task completion time when using the passive constraint. The left index, right middle, and right ring fingers are shown to have the least amount of over-grip, as well as the lowest time of non-contact with the tool, indicating the importance of these fingers for laparoscopic tool control.