1 April 2002
Engineers design new surgical instrument
University Park, Pa.—Engineers have developed new software that can design multitasking surgical tools.
Penn State engineers’ software helped design a tool that looks like tiny jaws but is able to bend around obstructions. The engineers are working in cooperation with surgeons from the university’s College of Medicine.
"The new software doesn’t replace a designer’s intuition and experience but suggests a topology or layout based on the designer’s specifications and the physical size constraints for the objective," said Dr. Mary Frecker, assistant professor of mechanical engineering and software team leader. "Our software was specifically developed to aid in designing instruments that do more than one thing."
Working with Dr. Randy S. Haluck, director of surgical simulation and minimally invasive surgery (MIS), the team used the software to develop a design for a single MIS instrument that can grasp, cut, pivot, and bend around obstructions.
In minimally invasive surgery, also known as laparoscopy or endoscopy, doctors insert a video camera and long slender surgical tools through small incisions or ports in the body. The smaller incisions cause fewer traumas and decrease postoperative pain, recovery time, and mortality. However, current MIS surgical tools give surgeons limited tactile feedback and dexterity.
Because most existing MIS tools are single-function instruments, the surgeon must constantly withdraw and reinsert new tools, Haluck said. Continually switching instruments can lengthen operation time and compromise safety.
To find common patterns of instrument exchange, the Penn State team studied videotapes of 29 surgical procedures and identified sequences in which multifunctionality could improve efficiency.
The study showed that exchanges between the scissors and graspers occur frequently, particularly in gall bladder removal operations, one of the most frequently performed MIS procedures. So the design incorporated grasping and cutting into the new instrument. Penn State applied for a patent on the software.
One version of the multifunctional tool, small enough to insert into a 5-millimeter incision, is already in prototype. Haluck said he wants to begin testing it in a laparoscopic trainer box very soon and will conduct animal tests within six months. The tool consists of tiny stainless-steel jaws that function as miniature scissors, with blades the size of rice grains, at the end of a long insertion rod. The jaws also function as graspers when the surgeon flips a switch on the instrument handle. Using other switches on the handle, the surgeon can also rotate the blades to acute right or left angles to get around obstructions.