Effects of Targeted Assistance and Perturbations on the Relationship Between Pelvis Motion and Step Width in People With Chronic Stroke

Reimold, Nicholas K.; Knapp, Holly A.; Chesnutt, Alyssa N.; Agne, Alexa; Dean, Jesse C.

doi:10.1109/tnsre.2020.3038173

Cited by 11 publications

(10 citation statements)

References 58 publications

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“…Future experiments could gain causal insight by manipulating biomechanical gait metrics and determining whether clinical balance measures change in parallel. For example, we have demonstrated that targeted perturbations can influence step width modulation in both neurologically-intact controls [33] and PwCS [27], with a primary effect on ρFP [26]. It is presently unclear whether an intervention targeting increased paretic ρFP would produce parallel improvements in clinical balance measures.…”

Section: Discussionmentioning

confidence: 99%

“…Following prior methods 32, 40, 41 , throughout each step we calculated the mediolateral displacement of the pelvis (relative to the stance heel at the start of the step) and the mediolateral velocity of the pelvis, with the positive direction defined as toward the swing leg. Pelvis displacement and velocity trajectories within each step were resampled to create 101-sample vectors, allowing us to perform analyses across these time-normalized steps.…”

Section: Methodsmentioning

confidence: 99%

“…For each step, we calculated step width as the mediolateral displacement between the stance heel at the start of the step and the swing heel at the end of the step. Following prior methods used to quantify step width modulation [22,26,27], we calculated the partial correlation between step width and mediolateral pelvis displacement at the start of the step (ρSW), accounting for mediolateral pelvis velocity. Our use of partial correlations rather than R 2 values is due to the presence of negative partial correlation values in some PwCS, which can artificially inflate R 2 values [22].…”

Section: Methodsmentioning

confidence: 99%

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Relationships between mediolateral step modulation and clinical balance measures in people with chronic stroke

Howard

Reimold

Knight

et al. 2022

Preprint

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BackgroundMany people with chronic stroke exhibit walking balance deficits, which are linked with increased fall risk and decreased balance confidence. One potential contributor to these deficits is a decreased ability to adjust where the paretic foot is placed based on pelvis motion, which is an important factor in mediolateral walking balance.ObjectiveThe objective of this study was to investigate altered stepping behavior for steps taken with the paretic leg, and to explore the relationship between this behavior and clinical measures of balance and balance confidence.Methods.93 individuals with chronic stroke walked on a treadmill and completed a series of common clinical tests. We used partial correlations to quantify the step-by-step relationship between mediolateral pelvis displacement and both step width (ρSW) and mediolateral foot placement relative to the pelvis (ρFP), a metric that focuses on swing leg repositioning.ResultsρSW was weaker for steps taken with the paretic leg, whereas ρFP did not differ between non-paretic and paretic steps. Participants who walked faster had larger ρSW and ρFP values, but instructing participants to walk faster did not consistently increase ρSW or ρFP for paretic steps. Significant, albeit weak, relationships were observed between paretic ρSW and Functional Gait Assessment score, as well as between paretic ρFP and Activities-Specific Balance Confidence score, fear of falling, and fall history.ConclusionsA reduced ability to adjust where the paretic foot lands when taking a step may discourage fast walking speeds after a stroke and contribute to clinical observations of decreased walking balance.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Relationships between mediolateral step modulation and clinical balance measures in people with chronic stroke

Howard

Reimold

Knight

et al. 2022

Preprint

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“…Similarly, individuals with lower limb amputation or post-stroke patients exhibit a gait with larger step width compared to non-disabled peers [17]- [20]. It has been postulated that this behavior is a result of poorer sensorimotor integration, where individuals after stroke fail to accurately integrate the position of their stance limb and pelvis to then place their swing foot appropriately [21]. Despite increased metabolic cost [22], [23], these populations prefer to walk with wider steps, implying the prioritization of stability and balance during the gait.…”

Section: Introductionmentioning

confidence: 99%

Abduction/Adduction Assistance from Powered Hip Exoskeleton Enables Modulation of User Step Width During Walking

Alili¹,

Fleming²,

Nalam³

et al. 2023

Preprint

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Abstract-Using wearable robotics to modulate step width in normal walking for enhanced mediolateral balance has not been demonstrated in the field. We designed a bilateral hip exoskeleton with admittance control to power hip abduction and adduction to modulate step width. Objective: As the first step to show its potential, the objective of this study was to investigate how human’s step width reacted to hip exoskeleton’s admittance control parameter changes during walking. Methods: Ten non-disabled individuals walked on a treadmill at a self-selected speed, while wearing our bilateral robotic hip exoskeleton. We used two equilibrium positions to define the direction of assistance. We studied the influence of multiple stiffness values in the admittance control on the participants’ step width, step length, and electromyographic (EMG) activity of the gluteus medius. Results: Step width were significantly modulated by the change of stiffness in exoskeleton control, while step length did not show significant changes. When the stiffness changed from zero to our studied stiffness values, the participants’ step width started to modulate immediately. Within 4 consecutive heel strikes right after a stiffness change, the step width showed a significant change. Interestingly, EMG activity of the gluteus medius did not change significantly regardless the applied stiffness and powered direction. Conclusion: Tuning of stiffness in admittance control of a hip exoskeleton, acting in mediolateral direction, can be a viable way for controlling step width in normal walking. Unvaried gluteus medius activity indicates that the increase in step width were mainly caused by the assistive torque applied by the exoskeleton. Significance: Our study results pave a new way for future design and control of wearable robotics in enhancing mediolateral walking balance for various rehabilitation applications.

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“…The degree of foot placement control has been shown to increase as an after-effect following training sessions within a perturbing force-field, both in stroke patients [12], and in neurologically intact individuals [13, 14]. Even in neurologically intact individuals, CoM variations are not entirely accounted for by subsequent modulation in foot placement [5].…”

Section: Introductionmentioning

confidence: 99%

Force-field perturbations and muscle vibration strengthen stability-related foot placement responses during steady-state gait

van Leeuwen,

Bruijn,

Dean

2023

Preprint

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Mediolateral gait stability can be maintained by coordinating our foot placement with respect to the center-of-mass (CoM) kinematic state. Neurological impairments can reduce the degree of foot placement control. For individuals with such impairments, interventions that could improve foot placement control could thus contribute to improved gait stability. In this study we aimed to better understand two potential interventions, by investigating their effect in neurologically intact individuals. The degree of foot placement control can be quantified based on a foot placement model, in which the CoM position and velocity during swing predict subsequent foot placement. Previously, perturbing foot placement with a force-field resulted in an enhanced degree of foot placement control as an after-effect. Moreover, muscle vibration enhanced the degree of foot placement control through sensory augmentation whilst the vibration was applied. Here, we replicated these two findings and further investigated whether Q1) sensory augmentation leads to an after-effect and Q2) whether combining sensory augmentation with force-field perturbations leads to a larger after-effect, as compared to force- field perturbations only. In addition, we evaluated several potential contributors to the degree of foot placement control, by considering foot placement errors, CoM variability and the CoM position gain (βpos) of the foot placement model, next to the R2 measure as the degree of foot placement control. Sensory augmentation led to a higher degree of foot placement control as an after-effect (Q1). However, combining sensory augmentation and force-field perturbations did not lead to a larger after-effect, as compared to following force-field perturbations only (Q2). Furthermore, we showed that, the improved degree of foot placement control following force- field perturbations and during/following muscle vibration, did not reflect diminished foot placement errors. Rather, participants demonstrated a stronger active response (higher βpos) as well as higher CoM variability.

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Effects of Targeted Assistance and Perturbations on the Relationship Between Pelvis Motion and Step Width in People With Chronic Stroke

Cited by 11 publications

References 58 publications

Relationships between mediolateral step modulation and clinical balance measures in people with chronic stroke

Relationships between mediolateral step modulation and clinical balance measures in people with chronic stroke

Abduction/Adduction Assistance from Powered Hip Exoskeleton Enables Modulation of User Step Width During Walking

Force-field perturbations and muscle vibration strengthen stability-related foot placement responses during steady-state gait

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