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Updated: May 13, 2026
Training Persons with Spinal Cord Injury to Ambulate Using a Powered Exoskeleton
Published on: June 16, 2016
Exoskeleton frontal and sagittal plane hip torque improves propulsion and transient stability during walking in
Dante Archangeli1, Andrew Gunnell1,2, Owen Winship1
1Department of Mechanical Engineering, Steve Sanghi College of Engineering, University of Northern Arizona, Flagstaff, AZ, USA.
Background:
Millions of people around the world experience post-stroke hemiparesis, making it difficult to move one side of the body. Hemiparesis impairs an individual's muscle strength and coordination which limits gait speed, efficiency, and endurance and contributes to reduced community participation. These limitations in strength and control also negatively impact balance, leading to a high prevalence of instability, falls, and fall-related injuries. Assistive technologies like powered exoskeletons that apply torques to the hips in the sagittal plane (hip flexion and extension) and frontal plane (hip abduction and adduction) may benefit both gait efficiency and stability in hemiparetic populations.
Methods:
In this study, we investigate the impact of exoskeleton-delivered frontal and sagittal plane hip torque in eight individuals with hemiparesis. Participants completed two-minute walking bouts on an instrumented treadmill with no exoskeleton, and then with the exoskeleton applying phase-based flexion and extension assistance. They then completed a series of abduction torque trials, in which they walked with the exoskeleton-supplied sagittal-plane assistance for 10 strides, and then sagittal-plane assistance and constant abduction torque for 10 strides. The abduction torque series consisted of four levels of abduction torque, each repeated 5 times, in random order.
Results:
Compared to steady-state walking without the exoskeleton, the application of sagittal plane torques significantly increased propulsive forces at push-off for the non-paretic limb by 0.83 ± 0.32% BW (p = 0.0373) and had little impact on step width or margin of stability. In the transient period following onset, hip abduction torques significantly increased step width by 0.053 ± 0.011 m (adjusted p < 0.025) and margin of stability for the paretic and non-paretic limb by 0.039 ± 0.006 m (adjusted p < 0.025) and 0.014 ± 0.004 m (adjusted p = 0.01), respectively. These outcomes are correlated with the level of abduction assistance.
Conclusion:
These results provide initial evidence supporting the use of a hip exoskeleton to impact foot placement, margin of stability, and propulsion in individuals with hemiparesis, which may benefit both gait efficiency and stability.
