The Doctorand EngineerWill See You NowEngineers and doctors collaborate to improve medical techniquesDr. Jon Wagner enters a brightly lit surgery suite and examineshis patient’s broken jawbone. Then Wagner selects a three-inchlong, thick titanium plate from an orthopedic implant kit andmeasures the plate against his patient’s jaw line. Too big. Heselects another plate. Still too big. And another. Too small. OnceWagner finds a plate that fits, he begins the painstaking process<strong>of</strong> bending and shaping the hard metal to match the contours<strong>of</strong> the patient’s face. Finally, he screws the plate into the brokenbones and finishes the surgery. The process, which can takewell over three hours, is difficult and expensive consideringoperating room costs exceed $2,000 an hour.Wagner has earned a M.D., a D.D.S. and is associate pr<strong>of</strong>essor inthe Division <strong>of</strong> Plastic Surgery at the <strong>UNM</strong> <strong>School</strong> <strong>of</strong> Medicine’sDepartment <strong>of</strong> Surgery. He knew there had to be a better way.02 <strong>UNM</strong> <strong>Engineering</strong>
Tariq Khraishi and Scott Lovald are developingplates designed to cut corrective jaw surgery timeand post-operative complications almost in half.The fun, but challengingpart <strong>of</strong> working withdoctors is that they havedifferent pr<strong>of</strong>icienciesthan engineers. We talkabout the same things,but we describe themin different terms.Tariq KhraishiHe hypothesized that the smaller, easier to attach plates heused to fix other facial fractures would work on the jaw. Butcould the plates withstand the powerful forces in the jaw?Wagner and his colleagues conducted their own tests to findout. “We were simulating a jaw using levers and beams andthen applying pressure until the plates broke. It was prettyrudimentary experimentation,” says Wagner.Searching for Sophisticated SolutionsWith no definitive answers from their tests, the doctors turnedtheir sights across campus to the Mechanical <strong>Engineering</strong>Department and Tariq Khraishi, associate pr<strong>of</strong>essor <strong>of</strong>mechanical <strong>engineering</strong> and expert in materials science andfracture mechanics. Khraishi and graduate student Scott Lovald,’06 Manufacturing <strong>Engineering</strong>, MBA, were the perfect partnersfor Wagner’s team. “Collaborating across campus has been sucha novel concept,” says Wagner. “I would still be doing archaicstudies, but with the engineers it quickly became a verysophisticated problem-solving pursuit.”Stryker Leibinger, a medical implant manufacturer, fundedthe multidisciplinary team’s research with a $150,000 fiveyearfellowship. It was the largest fellowship donated directlyto the Mechanical <strong>Engineering</strong> Department and the first tobe dedicated to biomechanics research. The first fellowshiprecipient was graduate student Victor Caraveo in 2006,followed by Julie Kimsal in 2007. Both have been studying theeffect <strong>of</strong> different bite forces and fracture locations, includingfracture surface friction, on fracture healing and fixation.Before Khraishi and Lovald could begin their research, thedoctors and engineers had to learn each other’s processes andjargon. “The fun, but challenging part <strong>of</strong> working with doctors isthat they have different pr<strong>of</strong>iciencies than engineers,” explainsKhraishi. “We talk about the same things, but we describe themin different terms.”From Medical to MechanicalAfter learning about the anatomy <strong>of</strong> the jaw and Wagner’shypothesis, the engineers created a three-dimensional digitalmodel <strong>of</strong> the jaw based on CT scans from an actual patient. Themodel replicated the jaw’s parabolic shape, the various forcesexerted upon the jaw, and the exact material qualities <strong>of</strong> thedifferent tissue and bone types in the jaw. The modeling processrequired two s<strong>of</strong>tware programs and months <strong>of</strong> meticulous work.Then the team used the model to analyze how well differenttypes <strong>of</strong> plates stabilized jaw fractures. The jaw’s complexmovement and materials required a robust analysis tool.Khraishi had just the thing: finite element analysis, a techniquethat solves <strong>engineering</strong> problems in complex structures.“Basically, you take one impossibly complicated problem andbreak it up into a number <strong>of</strong> reasonably complicated problems,”explains Khraishi. “By knowing how the part behaves, you canunderstand how the whole behaves.”Khraishi and Lovald used finite element analysis to quantifybite force, muscle movement, stress on the screws that hold theplates in place, and finally how different plate designs stabilized<strong>UNM</strong> <strong>Engineering</strong> 03
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