Experimental Biomechanics Lab Gives Students Hands-on Experience Evaluating Joint Replacements

The fall 2019 edition of the University of Denver Magazine is now out! This story originally published in the magazine. To view all the stories from the fall magazine, including feature stories on Chancellor Emerita Rebecca Chopp and DU's role in the success of the Denver Green School, please visit magazine.du.edu. 

It’s a Thursday in early June, and at the Ritchie School for Engineering and Computer Science’s Experimental Biomechanics Lab, it’s time to replace some knees. Ten of them, in fact. 

On hand for the job: One highly skilled surgeon; a smattering of students to help Chadd Clary, of the Department of Mechanical and Materials Engineering, monitor and collect data; and five cadavers, each of which will host two of the substitute knees.  

As the day progresses, the surgeon tries a range of procedures for the replacements. Once the new devices are in place, the surgeon bends and extends each knee to gauge flexion and range of motion. The engineers, meanwhile, tend to their data-capture tasks — made more difficult when conducted with fingers crossed. If all adheres to plan, the day’s work could inform how other surgeons implant a new generation of replacements into living humans. 

“The nice thing about working in our lab is we’re very practical,” says Clary, noting that the many evaluation projects underway could make a difference in mere months, affecting everything from implant design to a patient’s satisfaction with a procedure.

Launched in 2016 as a complement to the Ritchie School’s extensive orthopedic biomechanics enterprise, the lab not only provides evaluation of the surgical techniques associated with joint replacement; it also tests devices in the design stage. These studies, Clary says, typically are commissioned by manufacturers seeking independent confirmation of their own product research. They rely on the DU lab to identify design glitches, verify product claims and help secure FDA approval. 

“Companies are out there developing new devices, and they want to be able to put them into patients. But they never put them into patients first,” he says. 

The summer before his junior year, Gary Doan, now a master’s student in mechanical engineering, took on a research project that mixed his interest in medicine and anatomy with his aptitude for math and physics. “My project was exploring osteophytes, which are bone growths in the back part of the knee, and how they affect flexion and extension of the knee,” he says. 

Working with computer-aided drafting technology and a 3D printer, Doan was able to create synthetic osteophytes that were implanted in five cadavers just ahead of a total knee replacement, allowing surgeons to better understand how the growths can impede the performance of an artificial joint. 

Not all of the work requires surgeons and scalpels. Much of the testing enlists state-of-the-art technology to assess an implant’s durability and capacity. “We are using [highly sophisticated] machines to apply all the loading conditions the patient will experience: climbing stairs, stumbling, walking and deep knee bends,” Clary says.  

For master’s student Brittany Marshall, the opportunity to collaborate on device evaluations represents ideal preparation for a career in orthopedic advances. “You can learn so much from other [researchers] around you,” she says, adding that though her own thesis focuses on hip replacements, she has chipped in on projects related to shoulders and knees — all in the hope of helping others extend their activities or overcome pain. 

As Clary sees it, that hope is the lab’s reason for being. “A lot of times, when you do research, you’re working on areas that may be transformational, but your research may not actually affect people’s lives for years and years,” he says. But when a new device is introduced, it could help a senior citizen climb stairs or, for that matter, a quarterback toss a Hail Mary pass.