Hemiparesis, a primary cause of disability in the United States, weakens muscles, impairs motor control, and causes spasticity on one side of the body. This condition affects 80% of stroke survivors, leading to reduced mobility and diminished quality of life for millions. Walking demands intricate biomechanics, and even minor weakness on one side forces the opposite side to compensate, increasing energy expenditure by 60% compared to healthy individuals. Consequently, stroke survivors face slower speeds, fatigue, pain, and higher fall risks.
Innovative Hip Exoskeleton Solution
Engineers at the University of Utah’s John and Marcia Price College of Engineering, collaborating with the College of Health, have developed a portable hip exoskeleton that addresses this imbalance. In a recent study, the lightweight 5.5-pound device, worn around the hips and strapped to the thighs, reduced walking energy costs by nearly 20% for stroke survivors with hemiparesis. Battery-powered motors assist leg movement with each step, promoting efficient gait. Assistance levels are customized per user, with real-time intelligent controls delivering targeted boosts during hip lift and push-off.
Expert Insights on the Technology
“Improving quality of life after a stroke ranks among healthcare’s greatest challenges,” states senior author Tommaso Lenzi, associate professor in the Department of Mechanical Engineering. “Robotics now delivers measurable improvements.”
Prior exoskeletons targeted ankle issues like foot drop and poor propulsion. However, lead author Kai Pruyn, a graduate student in Lenzi’s HGN Lab for Bionic Engineering, notes, “Portable ankle exoskeletons failed to lower energy demands for stroke patients, prompting our hip-focused approach. Weak ankles often lead to hip overcompensation, which this device counters effectively.” Hip designs benefit from proximity to the body’s center of mass, enabling lighter builds and lower torque needs.
Lenzi’s team previously gained recognition for the Utah Bionic Leg, a top invention in 2023. While other groups showed hip exoskeletons boosting efficiency in healthy people, this marks the first success in hemiparesis patients.
Study Results and Participant Feedback
Researchers analyzed seven hemiparesis patients using motion-capture on an instrumented treadmill, with and without the exoskeleton, while measuring caloric expenditure. The device offloaded 30% of hip joint work, yielding an 18% drop in overall metabolic cost.
“For healthy walkers, it’s akin to shedding a 30-pound backpack,” explains co-author Bo Foreman, professor of Physical Therapy & Athletic Training. “For those with hemiparesis, it transforms daily life.”
Participants reported enhanced mobility. Stroke survivor Lidia shared, “At first, I couldn’t move my leg, but the device makes it much better now.” Her husband Marcellus added, “The exoskeleton handled some movement for her, and she improved even without it over time.”
Future Developments
Next, the team aims to refine the exoskeleton for safe home use and diverse activities, partnering with prosthetics experts for commercialization. “Strokes should not limit a person’s potential,” Lenzi affirms.
