Effects of Bilateral Assistance for Hemiparetic Gait Post-Stroke Using a Powered Hip Exoskeleton

Abstract

Hemiparetic gait due to stroke is characterized by an asymmetric gait due to weakness in the paretic lower limb. These inter-limb asymmetries increase the biomechanical demand and reduce walking speed, leading to reduced community mobility and quality of life. With recent progress in the field of wearable technologies, powered exoskeletons have shown great promise as a potential solution for improving gait post-stroke. While previous studies have adopted different exoskeleton control methodologies for restoring gait post-stroke, the results are highly variable due to limited understanding of the biomechanical effect of exoskeletons on hemiparetic gait. In this study, we investigated the effect of different hip exoskeleton assistance strategies on gait function and gait biomechanics of individuals post-stroke. We found that, compared to walking without a device, powered assistance from hip exoskeletons improved stroke participants’ self-selected overground walking speed by 17.6 ± 2.5% and 11.1 ± 2.7% with a bilateral and unilateral assistance strategy, respectively (p < 0.05). Furthermore, both bilateral and unilateral assistance strategies significantly increased the paretic and non-paretic step length (p < 0.05). Our findings suggest that powered assistance from hip exoskeletons is an effective means to increase walking speed post-stroke and tuning the balance of assistance between non-paretic and paretic limbs (i.e., a bilateral strategy) may be most effective to maximize performance gains.

Discovering individual-specific gait signatures from data-driven models of neuromechanical dynamics

“…Thus, although locomotor patterns can appear highly stereotyped, considerable inter- and intra-individual variability exists. Studies of locomotor behaviors have shown systematic differences in movement patterns based on a wide range of neural (Frisk et al, 2019; Ivanenko et al, 2003; Krogh et al, 2022; Young et al, 2022) and biomechanical perturbations (Genthe et al, 2018; Pan et al, 2022; Reisman et al, 2010; Wang et al, 2022) environmental challenges (D’souza et al, 2020; Larsen et al, 2022), psychological state (Attwood et al, 2021; Elkjær et al, 2022), social status (Steptoe and Zaninotto, 2020; Zaninotto et al, 2013), injury (Garcia et al, 2022; Jang and Wikstrom, 2022; Milner et al, 2022), and disease (Ijmker and Lamoth, 2012; Jonkers et al, 2009; Moura Coelho et al, 2022; Prosser et al, 2022; Russo et al, 2022; Troisi Lopez et al, 2022; Young et al, 2022). Furthermore, locomotor impairments can arise from a wide range of physiological and neurological changes, from the subtle changes that may be indicators of progressive disorders (e.g., aging, cognitive impairments) to profound impairments with brain injury (e.g., stroke, spinal cord injury) that can severely limit locomotor function.…”

Relationship Between Ankle Assistive Torque and Biomechanical Gait Metrics in Individuals After Stroke

“…Finally, a significant reduction in the metabolic cost of transport, increase in walking speed and reduction in the soleus activity when increasing PF peak torque were found for individuals with cerebral palsy [17], [18]. Furthermore, we have seen that the effects of the considered control parameters of interest resulted in stronger correlations with a wider range of gait parameters in comparison to other studies which analyzed the effects of varying hip and knee assistance on individuals after stroke [5], [12]- [15] (see Fig. 3…”

“…3.B) were considerably lower than the reported minimum adaptation time needed for unimpaired people to get used to powered ankle assistance [27]. This limitation is shared with the existing publications on the same topic for people with stroke (the total time spent walking with the exoskeleton was 20.00 ± 11.66 minutes [5], [11], [14], [15], the number of sessions was 1.17 ± 0.37 [5], [10]- [12], [14], [15], and the time per condition was 2.25 ± 0.83 [5], [11], [14], [15] without including our study; see Fig. 3.B-D) and cerebral palsy (the total time spent walking with the exoskeleton was 16.25 ± 0.00 minutes [17], the number of sessions was 5.66 ± 2.05 [16]- [18] and time per condition was 5.00 ± 0.00 [17]; see Fig.…”

“…To further develop adaptive control algorithms, there is a need for studies that analyze the biomechanical effects of varying exoskeleton controller parameters on post-stroke gait performance. However, to this day, only few studies on this topic can be found in the literature [5], [10]- [15]. These studies analyzed relations between peak assistive parameters of pelvis, hip and knee with joint and segment kinematics; circumduction; walking speed; propulsion force; step length, width and height; and swing, stance and double support time [5], [12]- [15].…”

“…However, to this day, only few studies on this topic can be found in the literature [5], [10]- [15]. These studies analyzed relations between peak assistive parameters of pelvis, hip and knee with joint and segment kinematics; circumduction; walking speed; propulsion force; step length, width and height; and swing, stance and double support time [5], [12]- [15]. Other studies focused on the effect of varying both the onset and the peak timing of the PF assistance on propulsion symmetry, ankle power and joint velocity [10], [11].…”