ODU M&S Research Team Develops Tool, Training Simulator for Surgical Procedure
June 07, 2012
Modeling and simulation researchers at Old Dominion University have teamed up with surgeons from Children's Hospital of The King's Daughters (CHKD) to continue a legacy of innovation that has made Norfolk the top location in the world for the treatment of a common chest deformity in children.
Pectus excavatum, Latin for "hollowed chest," causes several ribs and the sternum to grow abnormally. This produces a caved-in or sunken appearance of the chest, which can be present at birth or not develop until puberty.
Surgical correction of pectus excavatum was a complex and somewhat brutal procedure until CHKD surgeon Donald Nuss developed a minimally invasive technique to correct it in the 1990s. In the Nuss Procedure, which is now used around the world, the surgeon threads a curved metal bar under the sternum to push it out into a normal position. The bar is then anchored to the ribs and remains in place for approximately two years so the chest wall can harden in its new position. Then the bar is removed during a second surgery.
Nuss is now retired from CHKD, but his partners there and at Eastern Virginia Medical School continue to refine the procedure he developed and are currently collaborating with modeling and simulation researchers from ODU to do two things - design a new device to improve the procedure, and develop a hands-on simulation to train physicians to perform it safely.
Rick McKenzie, professor of modeling, simulation and visualization engineering in ODU's Frank Batten College of Engineering and Technology, is the principal investigator on a study to develop a tool to improve the process of extracting the metal bar during the second surgical procedure.
The tool - developed with Sebastian Bawab, professor of mechanical engineering; doctoral engineering student Krzysztof Rechowicz; and Dr. Robert Obermeyer of CHKD - is designed to make the extraction of the bar simpler and quicker.
In doing research for a device to help with the extraction, the ODU group wanted to look at the reason for the deformity, by determining the tissue properties of the pectus excavatum cartilage in vivo from current patients. That information will help in further understanding why the deformity occurs and how it can best be treated, McKenzie said.
The ODU device is designed to address the frustration surgeons had expressed about the previous extraction tool used for the Nuss Procedure, according to McKenzie. "They wanted a tool that could latch onto the bar and bend it in one movement."
The project was started in 2009. The prototype extraction device the researchers developed - consisting of two metal handles that latch onto the chest cavity bar - was tested on a patient in March, with promising results. A survey completed by the surgeon indicated that the Pectus Bar Extractor is easier to use, safer and allows a quicker extraction.
Now, the research team hopes to make several more of the extraction tools for the clinical trial, which could lead to commercialization of the device.
The other information being gathered about pectus excavatum patients is being rolled into a simulator created at ODU with collaboration from the pectus surgery group at CHKD, headed by Dr. Robert Kelly, chief of the Department of Surgery. The simulator is designed to train physicians how to perform the initial insertion procedure.
"Since the procedure requires the surgeons to insert a metal bar very close to the heart, reducing the risk associated with that during training is a very worthwhile goal," McKenzie said.
Using a video screen and a hand-held device that mimics the tool surgeons use to insert the metal bar into the chest cavity, the simulation will present the different types of pectus excavatum seen by surgeons at CHKD, using a patient-specific mathematical model.
ODU researchers and surgeons from CHKD will showcase the simulator, now in the final stages of development, at a pediatric surgery conference next June in Beijing.
"This could be used one day to train surgeons around the world," McKenzie said.