Karpowicz lost his leg when he was 27 years old. Now 67, he is participating in a clinical trial with a thought-controlled bionic leg that uses noninvasive technology to learn his movements and adjust with each step. Photograph courtesy of the Rehabilitation Institute of Chicago.
The June 9 issue of the Journal of the American Medical Association features the Rehabilitation Institute of Chicago (RIC) clinical trial that presents applications for the world’s first thought-controlled bionic prosthetic leg that does not require nerve redirection surgery or implanted sensors. Levi Hargrove, PhD, led this research at RIC’s Center for Bionic Medicine, where he is a research scientist. His team developed a system to use neural signals to safely improve limb control of a bionic leg.
“The bionic leg’s intelligent engineering allows amputees to transition seamlessly between sitting, standing, and walking, as well as ascending and descending stairs and ramps,” said Hargrove. “This leg’s intuitive thought control appears to work as well without nerve redirection surgery and does not require implants to be placed into the body….”
Seven individuals with lower-limb amputations participated in RIC’s randomized, clinical trial, which was the first of its kind.
When nerves instruct muscles to contract, these contractions generate EMG signals. An advanced computer program at RIC analyzes these EMG signals from sensors on the robotic leg. The program instantaneously decodes the type of movement the user is trying to perform, then sends those commands simultaneously to the robotic leg’s motorized knee and ankle to produce coordinated movements.
Combining muscle signals with robotic sensors not only maximizes the system’s “intuition,” it does so without invasive surgery or implants. As a result, more individuals with lower-limb amputations than ever before could have access to a bionic leg.
With support from both the U.S. Army’s Congressionally Directed Medical Research Program and the National Institutes of Health, RIC is working to provide at-home bionic leg testing for members of the military and the general public in the next three to four years.
“Participating in this RIC study allows me to help advance scientific knowledge and preview the way of the future,” said study participant Terry Karpowicz, a sculptor who creates large-scale works. “This bionic leg lets me move naturally, like I did before my amputation. For the first time in more than 30 years, I can experience my environment without thinking about which movement I want to make, because this leg does the thinking for me.”
