Happenings RESEARCH ROUNDUP
Exoskeleton Facilitates Walking for Prosthesis Users University of Utah researchers have developed a prototype exoskeleton to reduce above-knee prosthesis users’ exertion when walking. Led by Tommaso Lenzi, PhD, assistant professor of mechanical engineering and director of the university’s Bionic Engineering Lab, the research team is testing the lightweight exoskeleton, funded by a grant from the Congressionally Directed Medical Research Program. “Most of the research effort in the last 10 years has focused on restoring ankle pushoff with powered prostheses. This approach is sound but has some intrinsic drawbacks,” explains Lenzi. “Available
10
JANUARY 2022 | O&P ALMANAC
A study subject with above-knee limb loss walks on a treadmill using his prosthesis and wearing a lightweight exoskeleton. further and with less effort, improving their mobility in the community.” Lenzi’s team also is extending the use of the exoskeleton to more activities, like climbing stairs and slopes. “From a development standpoint, we are working on a new generation of our technology that will incorporate the feedback we have received from the research participants that have used our current prototype,” he said. “The goal is to partner with leaders in prosthetics and orthotics to make this technology available to the people who need it.”
PHOTO: Tommaso Lenzi, PhD/University of Utah
The researchers found the lightweight exoskeleton reduces the metabolic cost of walking by 15%.
powered prostheses are two or three times heavier than their passive counterpart, and the added mass of a powered prosthesis is distally suspended through the socket, which makes it feel even heavier than what it is.” His team sought alternatives and discovered that powered hip exoskeletons, which can be made very lightweight, could be effective because most of the compensatory movements in amputee gait happen at the residual hip, above the amputation. The new exoskeleton wraps around the wearer’s waist and leg, connecting to the user’s thigh above the amputation. The exoskeleton’s AI understands how the person moves by interpreting the information from the integrated position and load sensors, according to Lenzi. Then, it sends a command to the battery-powered electric motors assisting the residual limb in flexion and extension while adapting to the user’s gait speed and cadence. “In our study with individuals with above-knee amputation,” he said, “we found that our lightweight exoskeleton reduces the metabolic cost of walking by 15%, which is equivalent to taking off a 26-pound backpack.” The assistive technology would serve as an extra tool for clinicians, offering prosthetists “the freedom to use whatever prosthesis they believe is the most appropriate for their patients.” While the exoskeleton was developed primarily for individuals with above-knee amputation, “in general, anyone who may benefit from some extra assistance during walking can use it,” Lenzi said. His team is currently testing the exoskeleton with people with hemiparesis due to stroke. “We are quickly realizing that our lightweight exoskeleton has the potential to help many different people to walk
