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A foundation for the design and assessment of improved instruments for minimally invasive surgery Person, John Gunnar

Abstract

The goals of this project are to establish a foundation for research into the design and assessment of improved instruments for minimally invasive surgery (MIS). Minimally invasive surgery has exploded into general surgical practice in the last decade with the introduction of the laparoscopic cholecystectomy. Though beneficial to patients, the new technique is complicated by physical and mental challenges which make it difficult for surgeons to master. Improved instrumentation and teleoperators have the potential to ease the strain of performing the technique and improve surgeon performance. An experiment on the effects of physical constraints on surgeon performance is presented, in this report suggests that an economical and effective solution is to develop a teleoperator device constrained to 4 degrees of freedom which restores the natural motion mapping between the hand and instrument tip across the fulcrum point in the abdomen wall. A prototype 4 degree of freedom, mechanical teleoperator is constructed to'test this theory. The goal in developing this device is to map motion from the surgeon controlled master handle to the slave instrument tip within the surgical site, using only mechanical force transmission. Such a device has the potential to offer an economic solution to performance problems currently seen in MIS. Pitch and yaw motions are mapped between master and slave by direct mechanical linkage. Fundamental problems with a novel friction drive mechanism, however, prevent the prototype from functioning as anticipated, leaving the project open to future improvements. In order to effectively test for real improvements in surgeon performance, we also proposed a motion analysis system for measuring surgeon performance during actual surgeries. This system will be employed in future studies to validate surgical simulations in the laboratory which may be used to test and develop new instruments. A pilot study is performed to assess the potential of using the system to track the unconstrained motion of the surgeon's dominant arm over the course of a laparoscopic cholecystectomy. An ergonomic posture sampling study is performed to demonstrate the usefulness of the motion analysis system in this application.

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