UI prof’s ‘blade runner’ research aims at better prosthetic limbs
A University of Idaho professor’s research not only helped clear “blade runner” Oscar Pistorious to run in the Olympics - it also may open the door to a new generation of prosthetic limbs that could help amputees ranging from elite athletes to returning veterans win a race, return to combat, or just live a normal life.
Craig McGowan, an assistant professor of biological sciences at the UI in Moscow, was part of a research team that gathered with Pistorious at Rice University in 2008 for three days of intensive testing and experimentation. The results were presented to the Court of Arbitration for Sport in Lausanne, Switzerland, and persuaded the court to overturn its ban blocking Pistorious from the Olympics; he was born without fibulae in his lower legs, prompting their amputation when he was a baby.
“There was no evidence that would support an advantage, so he was allowed to run,” McGowan said. “We found that he produces less force against the ground, he can’t push off as hard against the ground as other athletes can. How much force you can push on the ground and how fast you can do that is one of the major determinants of how fast you can run.”
The researchers also found no decreased energy use in Pistorius because of the springy blades that sub for his lower legs and feet. “The results showed that really there is no energetic advantage to this,” McGowan said. “I think he is a very inspirational guy. He’s where he is because of a lot of hard work.”
The research didn’t end there, however. McGowan and other members of the team, who are from universities across the country but all have some connection to Harvard’s Concord Field Station, where McGowan earned his Ph.D and launched his interest in comparative biomechanics, continued looking into how prosthetics are used by high-level athletes. Studying unilateral amputees, people with one biological leg and one prosthetic leg, allowed them to make direct comparisons between the two limbs.
“I think this is just the beginning of understanding,” McGowan said. “The athletes allow us to look at really the extreme of adaptation - they’ve taken using these devices to a level that is just the pinnacle, so it gives us a great insight into what is possible. But the majority of people aren’t going to operate at that level.”
In a paper published in January this year, McGowan and four other researchers, including Hugh Herr of MIT and Roger Kram and Alena Grabowski of the University of Colorado, discovered new aspects of how muscles work as a runner runs faster.
“Humans and many other terrestrial animals, we basically run along like we’re using springs as legs,” McGowan said. “Our legs compress and re-extend every time we hit the ground.”
The researchers compared that spring action between a biological leg and a leg that was half prosthetic. “There were very significant differences,” he said. “As you measure them running at a steady speed but at increasing increments, the biological leg is able to increase its stiffness, so it can change how stiff it is - and the prosthetic limb can’t. It’s pretty well governed by the stiffness of that prosthetic spring.”
He said, “Essentially, it’s stiffening up the muscles. As you run faster and faster, your legs become stiffer and stiffer. We do that probably by stiffening up the muscles at the ankle.”
If a prosthetic limb could be developed that allowed its user to vary its stiffness at will, that runner could run more like an able-bodied one, and lose the disadvantage that comes from a non-varying stiffness.
“I think that is the way ahead for coming up with a prosthetic device that is more biological, that does truly emulate what the biological limb does,” McGowan said.
He and Grabowski are applying for a military research grant to continue their work. “There are a number of otherwise very healthy individuals coming back with limb loss, some of which want to get back to active duty, some just want to get back to living the life they had before,” McGowan said. “We’re hoping our research will help us design prosthetics that will help people just live healthy, active lives.”
Elite athletes who use prosthetics tend to compensate for their disadvantages with other mechanisms, McGowan said; Pistorius, for example, “swings his legs a little bit faster than other athletes do.” But the relentless pounding on the fixed-stiffness prosthetic limb can cause serious damage.
“A lot of individuals who use these devices end up getting osteoarthritis or lower back pain. … The joints are being loaded in ways that they weren’t designed for, basically,” McGowan said. Pistorius “gets a stiff back,” he said. “I don’t think he’s having any joint pain yet, but he’s still pretty young.”
McGowan, 38, is excited about the possibilities in his research; his UI students get to hear about it in his biology and comparative anatomy courses, where he cites examples from his research. He also teaches a nervous system class for the WWAMI program, which combines UI and the University of Washington medical school for a limited number of students seeking medical degrees each year.
McGowan followed a non-traditional route to his professorship; a native of the Pittsburgh area, he dropped out of Penn State after two years to travel the country and work on fishing boats in Alaska before returning to finish his degree in Flagstaff, Ariz. Along the way, he fell in love with the West.
“I do a lot of rock climbing and other outdoor sports, and it’s a beautiful place to live and be,” McGowan said. “So when I was looking for a faculty position, one of the things that was certainly a factor is balancing that quality of life and living in an area where I could get out and enjoy the environment as well as work at a really good school in a really good department.”
He’s taught at the UI for two years. And sometimes, when he’s out rock climbing, hiking or running, he looks at the movement of his legs or those of his climbing or hiking partners, or even animals they see, and gets ideas and questions to examine in his research.
“I usually just come up with lots of questions,” McGowan said with a laugh.