Training Wheels for Laparoscopic Surgery: Kinematic and Dynamic Constraints for Proper Tool Handling

Husam Wadi, BS1, Diana Diesen, MD2, Ann Majewicz, PhD1. 1University of Texas at Dallas, 2Children’s Medical Center

Learning and mastering laparoscopic skills is an involved and complicated process. It requires excellent hand-eye coordination, precise spatial reasoning skills, and the automation of non-intuitive arm movements. Learning these skills is especially difficult for pediatric residents who must additionally learn how to operate on fragile tissues within extremely small spaces. Given these constraints, precise, controlled, and gentle laparoscopic tool motions are essential.

An often overlooked aspect of laparoscopic skill training is proper handling of the surgical tool. Novice learns tend to over-grip the tool, which leads to less tool stability and control of the tool tip. Over time, the surgeons may learn that controlling the tool with their fingertips, and using an index finger for stabilization, leads to better tool control; however, this is not always the case. Constraint mechanisms, which promote appropriate tool handling, may enable novice learners to achieve this expert-level performance more quickly.

We have developed two prototype constraint mechanisms to enable proper tool handling. One mechanism is a kinematic constraint which physically prevents the user from over-gripping the tool. The mechanism is easily adjusted to fit the novice learner’s hand. A second mechanism operates under dynamic resistive control. Elastic constraints allow users to over-grip but provide increasing resistive force feedback, proportional to the amount of over-grip. Both of these passive devices can be 3D printed for less than $5 each, and can fit a variety of laparoscopic tools.

In the future, we will conduct a series of human subject studies with novice learners to improve the design of these mechanisms, as well as to determine whether kinematic or dynamic constraints lead to better long-term learning of surgical skills. Furthermore, we will conduct a theoretical and computational dynamic analysis of laparoscopic tools to study tool stability over a variety of operating conditions and grip types.

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