Mason Intern Works to Improve Prostheses—and Lives

Posted: May 22, 2013 at 4:17 pm, Last Updated: May 28, 2013 at 1:00 pm

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By Cathy Cruise

Casey Wilkison (on left) and associate professor and mentor Nelson Cortes attend the 2nd Annual Celebration of Student Scholarship. Cortes received the 2013 OSCAR Mentoring Excellence Award. Photo by Evan Cantwell/Creative Services/George Mason University

Casey Wilkison (on left) and associate professor and mentor Nelson Cortes attend the 2nd Annual Celebration of Student Scholarship. Cortes received the 2013 OSCAR Mentoring Excellence Award and Wilkison is winner of this year’s award for Outstanding Student in Kinesiology. Photo by Evan Cantwell/Creative Services/George Mason University

Service members who are learning to adjust to life after amputations don’t need the added challenges of prostheses that are ill fitting or hard to manipulate.

Senior Casey Wilkison has been working to resolve issues with these devices through an internship with George Mason University and Walter Reed National Military Medical Center. Wilkison will receive her BS in health, fitness, and recreation resources, with a concentration in kinesiology, this summer. She is the winner of this year’s award for Outstanding Student in Kinesiology.

Wilkison’s interest in the field of prosthetics was sparked after seeing “Blade Runner” Oscar Pistorius participate in the Olympics, and upon learning that a family friend lost part of his leg in Afghanistan. For her Research Methods class, she chose to study unilateral lower-extremity amputees, or people with one amputated leg. By the time she took a biomechanics class with Nelson Cortes, associate professor at the College of Education and Human Development, she was hooked.

“I just loved it,” she says. “Dr. Cortes is a wonderful mentor and an incredible teacher. It took me a week in his class, and I knew I wanted to do it forever.”

During spring semester, Wilkison spent four days a week at Walter Reed’s “Gait Lab” within the hospital’s Military Advanced Training Center. As part of a case series she completed for a grant from the Office of Student Scholarship, Creative Activities, and Research, she used computer programs to perform gait analyses on patients with high-level (above the knee) lower limb amputations. Specifically, she studied two service members with a hip disarticulation on one side—an amputation through the hip joint capsule that has removed the entire lower extremity—and a transfemoral amputation on the other side, or an amputation that occurs through the femur.

The process began by putting motion capture markers and a metabolic mask on a patient wearing prosthetic legs. As the participant performed a walking trial across force plates, light reflecting from the markers was captured with infrared cameras around the room, and metabolic information—such as how much carbon dioxide and calories were expended during the exercise—was compiled.

Wilkison used computer programs to reconstruct the participants as stick figures and mark the foot strikes, then transformed those images into skeletons so, she says, “you really get to see the bigger picture” of their movements on the screen. She then helped compile reports of the biomechanical data.

“We combined the force plate data with the marker data,” she explains, “so we could see how symmetric their gait was, what they favored, what things were abnormal and need to be worked on. This will help service members with amputations to move more efficiently so they’re not so exhausted walking with their prostheses.”

The research studied not only how the patients walked with their prostheses using canes, but also how their movements affected their shoulders. Since patients with these specific types of amputations are not commonly seen—there have been 26 of them since 2001—there is “next to no research on them,” Wilkison says.

One of the subjects had been using prostheses on both legs for more than three years, the other one for less than a year. The man who had used his prostheses longer was found to walk much more efficiently. And even though he “put a good amount of force on both shoulders,” Wilkison says, “there was less of a difference between his two shoulders, possibly because he just got so good at walking.”

“We were looking at the net force on the entire shoulder joint to see if the arm opposite the higher amputation would take the greater brunt of the force because they’re having to support less limb. And we found that it did take more.”

While a third subject may soon participate in the study, Wilkison says the information obtained so far underscores the need for more research “to develop prostheses that are better suited for bilateral, high-level amputees to make their walking more efficient.”

Working beside people with such devastating injuries was an eye-opening experience, she says. While it was challenging to see such damage firsthand, it was also extremely rewarding to realize how optimistic the people she studied remain.

“I love working with military service members,” she says. “Some are missing three, four limbs. But they walk in a room and the first thing they do is start joking around. They’re so much happier than most people I encounter.”

Nelson Cortes leads the SMART Lab Team, Research and Development (STRiDE) group at Mason.

Nelson Cortes leads the SMART Lab Team, Research and Development (STRiDE) group at Mason.

Wilkison is the first Mason student to intern at the Walter Reed Gait Lab, and she was recommended by Cortes due to her involvement in the group he leads, the SMART Lab Team, Research and Development (STRiDE). Through the STRiDE group, Cortes mentors students and gives them the opportunity to be actively involved in research projects and journal clubs. It’s an opportunity he hopes others will consider pursuing.

“I would recommend students get involved with a biomechanics laboratory such as ours,” he says, “so they can have hands-on experience about the experimental procedures, concepts, and protocols.”

Cortes also plans to initiate more partnerships with Walter Reed in the future. “This is a young collaboration that is starting with Casey,” he says. “Hopefully, we will continue both from an internship perspective as well as from a research perspective.”

Wilkison has written up an abstract on her research and hopes to exhibit it as a poster presentation at the Biomedical Engineering Society Meeting this September. She plans to continue her studies, possibly in biomechanics, and says she may one day become a prosthetist—a person who creates, fits, and services prosthetic devices.

“Sadly,” she says, “that’s an in-demand job right now. And I’d love to work at Walter Reed someday. They’re the best.”

Write to Robin Herron at rherron@gmu.edu

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