Post-stroke Gait Rehabilitation Research Articles

We Will, We Will Shock You: Adaptive Versus Conventional Functional Electrical Stimulation in Individuals Post-Stroke.

Functional electrical stimulation (FES) is often used in post-stroke gait rehabilitation to address decreased walking speed, foot drop, and decreased forward propulsion. However, not all individuals experience clinically meaningful improvements in gait function with stimulation. Previous research has developed adaptive functional electrical stimulation (AFES) systems that adjust stimulation timing and amplitude at every stride to deliver optimal stimulation. The purpose of this work was to determine the effects of a novel AFES system on functional gait outcomes and compare them to the effects of the existing FES system. Twenty-four individuals with chronic post-stroke hemiparesis completed six four-minute walking trials on an adaptive and fixed-speed treadmill with no stimulation, stimulation from the existing FES system, and stimulation from the AFES system. There was no significant effect of stimulation condition on walking speed, peak dorsiflexion angle, or peak propulsive force. Walking speed was significantly faster and peak propulsive force was significantly larger on the adaptive treadmill than the fixed-speed treadmill (both p < 0.0001).Dorsiflexor stimulation timing was similar between stimulation conditions, but plantarflexor stimulation timing was significantly improved with the AFES system compared to the FES system (p = 0.0059). Variability between and within subjects was substantial, and some subjects experienced clinically meaningful improvements in walking speed, peak dorsiflexion angle, and peak propulsive force. However, not all subjects experienced benefits, suggesting that further research to characterize which subjects exhibit the best instantaneous response to FES is needed to optimize post-stroke gait rehabilitation using FES.

The Variable Stiffness Treadmill 2: Development and Validation of a Unique Tool to Investigate Locomotion on Compliant Terrains

Abstract Understanding legged locomotion in various environments is valuable for many fields, including robotics, biomechanics, rehabilitation, and motor control. Specifically, investigating legged locomotion in compliant terrains has recently been gaining interest for the robust control of legged robots over natural environments. At the same time, the importance of ground compliance has also been highlighted in poststroke gait rehabilitation. Currently, there are not many ways to investigate walking surfaces of varying stiffness. This article introduces the variable stiffness treadmill (VST) 2, an improvement of the first version of the VST, which was the first treadmill able to vary belt stiffness. In contrast to the VST 1, the device presented in this paper (VST 2) can reduce the stiffness of both belts independently, by generating vertical deflection instead of angular, while increasing the walking surface area from 0.20m2 to 0.74m2. In addition, both treadmill belts are now driven independently, while high-spatial-resolution force sensors under each belt allow for measurement of ground reaction forces and center of pressure. Through validation experiments, the VST 2 displays high accuracy and precision. The VST 2 has a stiffness range of 13kN/m to 1.5MN/m, error of less than 1%, and standard deviations of less than 2.2kN/m, demonstrating its ability to simulate low-stiffness environments reliably. The VST 2 constitutes a drastic improvement of the VST platform, a one-of-its-kind system that can improve our understanding of human and robotic gait while creating new avenues of research on biped locomotion, athletic training, and rehabilitation of gait after injury or disease.

Orthotist involvement in early gait rehabilitation after stroke: A cross-sectional survey of orthotists in the United Kingdom.

The role of the orthotist in early gait rehabilitation after stroke in the United Kingdom is currently poorly understood. The objective of this study was to capture current opinion and practice of orthotists on their role in early stroke gait rehabilitation in the United Kingdom. An anonymous web-based cross-sectional survey was developed and distributed to Health and Care Professions Council-registered orthotists by the mailing list of the British Association of Prosthetists and Orthotists professional body in the United Kingdom. Survey items were multiple-choice, Likert scale, or open-ended questions to explore the experiences and opinions of orthotists in early poststroke gait rehabilitation. Responses were received from 56 participants. Orthotists reported having regular contact with patients who had a stroke within their usual clinical caseload. Multidisciplinary care was not typical with 46% respondents "rarely" seeing patients who had a stroke in joint assessment with another clinician. Confidence in managing lower limb gait difficulties was high, with 89% of orthotists feeling able to recommend a lower limb orthotic treatment. Ninety-eight percent (n = 55) of respondents agreed that orthotic assessment should be an essential element of gait re-education after stroke; however, orthotists reported limited involvement within early stroke rehabilitation. UK orthotists surveyed in this study report that orthotic treatment is an important aspect of early gait rehabilitation after stroke. Respondents report barriers to multidisciplinary working, which may affect outcomes in this patient group.

Adaptive Functional Electrical Stimulation Delivers Stimulation Amplitudes Based on Real-Time Gait Biomechanics.

Functional electrical stimulation (FES) is often used in poststroke gait rehabilitation to decrease foot drop and increase forward propulsion. However, not all stroke survivors experience clinically meaningful improvements in gait function following training with FES. The purpose of this work was to develop and validate a novel adaptive FES (AFES) system to improve dorsiflexor (DF) and plantarflexor (PF) stimulation timing and iteratively adjust the stimulation amplitude at each stride based on measured gait biomechanics. Stimulation timing was determined by a series of bilateral footswitches. Stimulation amplitude was calculated based on measured dorsiflexion angle and peak propulsive force, where increased foot drop and decreased paretic propulsion resulted in increased stimulation amplitudes. Ten individuals with chronic poststroke hemiparesis walked on an adaptive treadmill with adaptive FES for three 2-min trials. Stimulation was delivered at the correct time to the dorsiflexor muscles during 95% of strides while stimulation was delivered to the plantarflexor muscles at the correct time during 84% of strides. Stimulation amplitudes were correctly calculated and delivered for all except two strides out of nearly 3000. The adaptive FES system responds to real-time gait biomechanics as intended, and further individualization to subject-specific impairments and rehabilitation goals may lead to improved rehabilitation outcomes.

Human-centered design of a novel soft exosuit for post-stroke gait rehabilitation

BackgroundStroke remains a major cause of long-term adult disability in the United States, necessitating the need for effective rehabilitation strategies for post-stroke gait impairments. Despite advancements in post-stroke care, existing rehabilitation often falls short, prompting the development of devices like robots and exoskeletons. However, these technologies often lack crucial input from end-users, such as clinicians, patients, and caregivers, hindering their clinical utility. Employing a human-centered design approach can enhance the design process and address user-specific needs.ObjectiveTo establish a proof-of-concept of the human-centered design approach by refining the NewGait® exosuit device for post-stroke gait rehabilitation.MethodsUsing iterative design sprints, the research focused on understanding the perspectives of clinicians, stroke survivors, and caregivers. Two design sprints were conducted, including empathy interviews at the beginning of the design sprint to integrate end-users’ insights. After each design sprint, the NewGait device underwent refinements based on emerging issues and recommendations. The final prototype underwent mechanical testing for durability, biomechanical simulation testing for clinical feasibility, and a system usability evaluation, where the new stroke-specific NewGait device was compared with the original NewGait device and a commercial product, Theratogs®.ResultsAffinity mapping from the design sprints identified crucial categories for stakeholder adoption, including fit for females, ease of donning and doffing, and usability during barefoot walking. To address these issues, a system redesign was implemented within weeks, incorporating features like a loop-backed neoprene, a novel closure mechanism for the shoulder harness, and a hook-and-loop design for the waist belt. Additional improvements included reconstructing anchors with rigid hook materials and replacing latex elastic bands with non-latex silicone-based bands for enhanced durability. Further, changes to the dorsiflexion anchor were made to allow for barefoot walking. Mechanical testing revealed a remarkable 10-fold increase in durability, enduring 500,000 cycles without notable degradation. Biomechanical simulation established the modularity of the NewGait device and indicated that it could be configured to assist or resist different muscles during walking. Usability testing indicated superior performance of the stroke-specific NewGait device, scoring 84.3 on the system usability scale compared to 62.7 for the original NewGait device and 46.9 for Theratogs.ConclusionThis study successfully establishes the proof-of-concept for a human-centered design approach using design sprints to rapidly develop a stroke-specific gait rehabilitation system. Future research should focus on evaluating the clinical efficacy and effectiveness of the NewGait device for post-stroke rehabilitation.

Improving walking via real-time visual feedback after stroke in treadmill training (RE-VISIT): a protocol for randomized controlled trial

BACKGROUND: After a stroke, most patients often suffer reduced walking ability and balance. Restoring walking ability and improving balance are major goals of stroke rehabilitation. Treadmills are often used in clinical setups to achieve these goals. Adding dimensions to the visual feedback in addition to the mirror for real-time frontal view is proven to enhance the gait. It is, therefore, important to design additional real-time visual feedback in treadmill training, in particular for the sagittal view involved side. OBJECTIVE: The objective of this study is to test if the real-time sagittal visual feedback during treadmill training is superior to the conventional mirror feedback treadmill training program of equivalent intensity in improving walking speed and balance after stroke. METHODS/DESIGN: The RE-VISIT trial (Real-time Visual feedback after Stroke in Treadmill training) is registered in the Clinical Trial Registry of India (CTRI/2023/10/058299). In this two-arm randomized control trial, which will be a single-blinded study, 42 eligible stroke survivors undergoing rehabilitation will be randomly allocated (1:1 ratio) to either real-time visual sagittal feedback along with front mirror (experimental) group or only front mirror treadmill training (control) group, all the participants will receive 15 sessions of treadmill training for up to 15 min at a safe self-selected speed over 5-6 weeks. The RE-VISIT (experimental) group will receive real-time, visual sagittal view feedback of the involved lower limb trajectory along with the routine front mirror view during treadmill training and will be asked to modify their gait pattern. The control group will receive treadmill walking training only with the routine front mirror view feedback. Clinical and gait assessments will be conducted at the baseline, immediately following the final session of training, and at the 9th week during follow-up. The outcome measures of interest are walking speed (primary) and balance (secondary), which will be measured prior to baseline, post 15 sessions of training, and at the 9th week following training. DISCUSSION: This REVISIT trial will provide insight and contribute to the existing innovation and modifications of incorporating real-time visual feedback during treadmill training in post-stroke gait rehabilitation. The findings will help the better designing of a gait rehabilitation program with a treadmill for post-stroke subjects to improve walking speed, and balance for those who have greater difficulties in community ambulation. We anticipate that those in the REVISIT training will demonstrate improved walking ability.

A VR-based Treadmill Training System for Post-stroke Gait Rehabilitation.

Virtual reality (VR) has the potential to enhance rehabilitation by creating simulated multiple training environments, thereby maximizing the implementation of motor learning principles. However, previous use of VR-based treadmill training to improve post-stroke gait function is limited by high cost and a lack of adherence to post-stroke gait rehabilitation principles in system design. This paper describes the development of a gait rehabilitation system that integrates treadmill gait training with VR technology to create a virtual rehabilitation setting with gait training tasks and real-time performance feedback. The proposed system targets post-stroke patients and integrates low-cost sensor and rehabilitation principles to allow remote training and maximize training efficacy.Clinical Relevance-This system is developed with an emphasis on rehabilitation and motor learning principles.

Using robot-assisted stiffness perturbations to evoke aftereffects useful to post-stroke gait rehabilitation.

Stroke is a major global issue, affecting millions every year. When a stroke occurs, survivors are often left with physical disabilities or difficulties, frequently marked by abnormal gait. Post-stroke gait normally presents as one of or a combination of unilaterally shortened step length, decreased dorsiflexion during swing phase, and decreased walking speed. These factors lead to an increased chance of falling and an overall decrease in quality of life due to a reduced ability to locomote quickly and safely under one's own power. Many current rehabilitation techniques fail to show lasting results that suggest the potential for producing permanent changes. As technology has advanced, robot-assisted rehabilitation appears to have a distinct advantage, as the precision and repeatability of such an intervention are not matched by conventional human-administered therapy. The possible role in gait rehabilitation of the Variable Stiffness Treadmill (VST), a unique, robotic treadmill, is further investigated in this paper. The VST is a split-belt treadmill that can reduce the vertical stiffness of one of the belts, while the other belt remains rigid. In this work, we show that the repeated unilateral stiffness perturbations created by this device elicit an aftereffect of increased step length that is seen for over 575 gait cycles with healthy subjects after a single 10-minintervention. These long aftereffects are currently unmatched in the literature according to our knowledge. This step length increase is accompanied by kinematics and muscle activity aftereffects that help explain functional changes and have their own independent value when considering the characteristics of post-stroke gait. These results suggest that repeated unilateral stiffness perturbations could possibly be a useful form of post-stroke gait rehabilitation.

A Cable-driven Exoskeleton with Personalized Assistance Improves the Gait Metrics of People in Subacute Stroke.

Most stroke survivors have mobility deficits and show a pathological gait pattern. Seeking to enhance the gait performance among this population, we have developed a hybrid cable-driven lower limb exoskeleton (called SEAExo). This study aimed to determine the effects of SEAExo with personalized assistance on immediate changes in gait performance of people after stroke. Gait metrics (i.e., the foot contact angle, knee flexion peak, temporal gait symmetry indices) and muscle activities were the primary outcomes to evaluate the assistive performance. Seven subacute stroke survivors participated and completed the experiment with three comparison sessions, i.e., walking without SEAExo (served as baseline) and without/with personalized assistance, at their preferred walking speeds. Compared to the baseline, we observed increases in the foot contact angle and knee flexion peak by 70.1% (p < 0.05) and 60.0% (p < 0.05) with personalized assistance. Personalized assistance contributed to the improvements in temporal gait symmetry of more impaired participants (p < 0.05), and it led to a 22.8% and 51.3% (p < 0.05) reduction in the muscle activities of ankle flexor muscles. These results demonstrate that SEAExo with personalized assistance has the potential to enhance post-stroke gait rehabilitation in real-world clinical settings.

A continuous statistical-geometric framework for normative and impaired gaits.

A quantitative analysis of human gait patterns in space-time provides an opportunity to observe variability within and across individuals of varying motor capabilities. Impaired gait significantly affects independence and quality of life, and thus a large part of clinical research is dedicated to improving gait through rehabilitative therapies. Evaluation of these paradigms relies on understanding the characteristic differences in the kinematics and underlying biomechanics of impaired and unimpaired locomotion, which has motivated quantitative measurement and analysis of the gait cycle. Previous analysis has largely been limited to a statistical comparison of manually selected pointwise metrics identified through expert knowledge. Here, we use a recent statistical-geometric framework, elastic functional data analysis (FDA), to decompose kinematic data into continuous 'amplitude' (spatial) and 'phase' (temporal) components, which can then be integrated with established dimensionality reduction techniques. We demonstrate the utility of elastic FDA through two unsupervised applications to post-stroke gait datasets. First, we distinguish between unimpaired, paretic and non-paretic gait presentations. Then, we use FDA to reveal robust, interpretable groups of differential response to exosuit assistance. The proposed methods aim to benefit clinical practice for post-stroke gait rehabilitation, and more broadly, to automate the quantitative analysis of motion.

Synthesis of a six-bar mechanism for generating knee and ankle motion trajectories using deep generative neural network

Robotic exoskeletons have demonstrated their effectiveness in post-stroke gait rehabilitation therapy. Nevertheless, further research is being conducted to improve existing rehabilitation exoskeletons in terms of ease-of-use and innovative design. Previously, the adaptation of linkage-based mechanisms for rehabilitation exoskeletons has been considered an option. However, finding linkage parameters that will produce the required gait trajectories using a linkage-based exoskeleton, is quite challenging. It is furthermore challenging to obtain parameters of a linkage-based mechanism designed for a gait rehabilitation task that has to produce two trajectories (for knee and ankle joints) simultaneously. In this work, we propose Deep Generative Neural Networks (DGNN) to obtain a set of optimal dimensions and parameters for the Stephenson III six-bar linkage-based gait exoskeleton. The proposed methodology demonstrates high efficacy in determining the linkage parameters for various target trajectories. The proposed framework, once trained, can accurately predict mechanism parameters to achieve two joint trajectories simultaneously. Subsequent to developing the model, walking trajectories from healthy human subjects are given to the model to determine the optimal linkage dimensions of the gait rehabilitation exoskeleton. The proposed model can be used to assist designers in quickly determining the optimized linkage dimensions of linkage-based mechanisms that can provide various target trajectories.

Robotic Biofeedback for Post-Stroke Gait Rehabilitation: A Scoping Review.

This review aims to recommend directions for future research on robotic biofeedback towards prompt post-stroke gait rehabilitation by investigating the technical and clinical specifications of biofeedback systems (BSs), including the complementary use with assistive devices and/or physiotherapist-oriented cues. A literature search was conducted from January 2019 to September 2022 on Cochrane, Embase, PubMed, PEDro, Scopus, and Web of Science databases. Data regarding technical (sensors, biofeedback parameters, actuators, control strategies, assistive devices, physiotherapist-oriented cues) and clinical (participants’ characteristics, protocols, outcome measures, BSs’ effects) specifications of BSs were extracted from the relevant studies. A total of 31 studies were reviewed, which included 660 stroke survivors. Most studies reported visual biofeedback driven according to the comparison between real-time kinetic or spatiotemporal data from wearable sensors and a threshold. Most studies achieved statistically significant improvements on sensor-based and clinical outcomes between at least two evaluation time points. Future research should study the effectiveness of using multiple wearable sensors and actuators to provide personalized biofeedback to users with multiple sensorimotor deficits. There is space to explore BSs complementing different assistive devices and physiotherapist-oriented cues according to their needs. There is a lack of randomized-controlled studies to explore post-stroke stage, mental and sensory effects of BSs.

Immediate Biomechanical Effects of Providing Adaptive Assistance With an Ankle Exoskeleton in Individuals After Stroke

Recent studies on ankle exoskeletons have shown the feasibility of this technology for post-stroke gait rehabilitation. The main contribution of the present work is a comprehensive experimental analysis and protocol that focused on evaluating a wide range of biomechanical, usability and users’ perception metrics under three different walking conditions: without exoskeleton, with an ankle exoskeleton unpowered, and with an ankle exoskeleton powered. To carry out this study, we developed the ABLE-S exoskeleton that can provide time-adapted ankle plantarflexion and dorsiflexion assistance. Tests with five participants with chronic stroke showed that walking with the ABLE-S exoskeleton significantly corrected foot drop by 25 % while reducing hip compensatory movements by 21 %. Furthermore, asymmetrical spatial gait patterns were significantly reduced by 51 % together with a significant increase in the average foot tilting angle at heel strike by 349 %. The total time to don, doff and set-up the device was of 7.86 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 2.90 minutes. Finally, 80 % of the participants indicated that they were satisfied with their walking performance while wearing the exoskeleton, and 60 % would use the device for community ambulation. The results of this study add to the existing body of evidence supporting that ankle exoskeletons can improve gait biomechanics for post-stroke individuals.

Adaptive treadmill walking encourages persistent propulsion

BackgroundAdaptive treadmills allow real-time changes in walking speed by responding to changes in step length, propulsion, or position on the treadmill. The stride-to-stride variability, or persistence, of stride time during overground, fixed-speed, and adaptive treadmill walking has been studied, but persistence of propulsion during adaptive treadmill walking remains unknown. Because increased propulsion is often a goal of post-stroke rehabilitation, knowledge of the stride-to-stride variability may aid rehabilitation protocol design. Research questionHow do spatiotemporal and propulsive gait variables vary from stride to stride during adaptive treadmill walking, and how do they compare to fixed-speed treadmill walking? MethodsEighteen young healthy subjects walked on an instrumented split-belt treadmill in the adaptive and fixed-speed modes for 10 minutes at their comfortable speed. Kinetic data was collected from the treadmill. Detrended fluctuation analysis was applied to the time series data. Shapiro-Wilk tests assessed normality and one-way repeated measures ANOVAs compared between adaptive, fixed-speed, and randomly shuffled conditions at a Bonferroni-corrected significance level of 0.0055. ResultsStride time, stride length, step length, and braking impulse were persistent (α > 0.5) in the adaptive and fixed-speed conditions. Adaptive and fixed-speed were different from each other. Stride speed was persistent in the adaptive condition and anti-persistent (α < 0.5) in the fixed-speed condition. Peak propulsive force, peak braking force, and propulsive impulse were persistent in the adaptive condition but not the fixed-speed condition (α ≈ 0.5). Net impulse was non-persistent in the adaptive and fixed-speed conditions. All variables were non-persistent in the shuffled condition. SignificanceDuring adaptive treadmill walking, increases in propulsive force and impulse persist for multiple strides. Persistence was stronger on the adaptive treadmill, where increased propulsion translates into increased walking speed. For post-stroke gait rehabilitation where increasing propulsion and speed are goals, the stronger persistence of adaptive treadmill walking may be beneficial.

Biofeedback for Post-stroke Gait Retraining: A Review of Current Evidence and Future Research Directions in the Context of Emerging Technologies.

Real-time gait biofeedback is a promising rehabilitation strategy for improving biomechanical deficits in walking patterns of post-stroke individuals. Because wearable sensor technologies are creating avenues for novel applications of gait biofeedback, including use in tele-health, there is a need to evaluate the state of the current evidence regarding the effectiveness of biofeedback for post-stroke gait training. The objectives of this review are to: (1) evaluate the current state of biofeedback literature pertaining to post-stroke gait training; and (2) determine future research directions related to gait biofeedback in context of evolving technologies. Our overall goal was to determine whether gait biofeedback is effective at improving stroke gait deficits while also probing why and for whom gait biofeedback may be an efficacious treatment modality. Our literature review showed that the effects of gait biofeedback on post-stroke walking dysfunction are promising but are inconsistent in methodology and therefore results. We summarize sources of methodological heterogeneity in previous literature, such as inconsistencies in feedback target, feedback mode, dosage, practice structure, feedback structure, and patient characteristics. There is a need for larger-sample studies that directly compare different feedback parameters, employ more uniform experimental designs, and evaluate characteristics of potential responders. However, as these uncertainties in existing literature are resolved, the application of gait biofeedback has potential to extend neurorehabilitation clinicians' cues to individuals with post-stroke gait deficits during ambulation in clinical, home, and community settings, thereby increasing the quantity and quality of skilled repetitions during task-oriented stepping training. In addition to identifying gaps in previous research, we posit that future research directions should comprise an amalgam of mechanism-focused and clinical research studies, to develop evidence-informed decision-making guidelines for gait biofeedback strategies that are tailored to individual-specific gait and sensorimotor impairments. Wearable sensor technologies have the potential to transform gait biofeedback and provide greater access and wider array of options for clinicians while lowering rehabilitation costs. Novel sensing technologies will be particularly valuable for telehealth and home-based stepping exercise programs. In summary, gait biofeedback is a promising intervention strategy that can enhance efficacy of post-stroke gait rehabilitation in both clinical and tele-rehabilitation settings and warrants more in-depth research.

User-driven treadmill walking promotes healthy step width after stroke

BackgroundWalking with user-driven treadmill control is believed to be more like overground walking than fixed-speed treadmill walking. Walking speed and ground reaction forces differ between overground and fixed-speed treadmill walking, but not between overground and user-driven treadmill walking in healthy and post-stroke subjects. However, studies assessing spatiotemporal gait parameters during user-driven treadmill walking are limited. This information may help confirm that user-driven treadmill walking is more like overground walking than fixed-speed treadmill walking, as well as inform the development of post-stroke gait rehabilitation programs. Research questionHow do spatiotemporal gait parameters for individuals post-stroke differ between fixed-speed and user-driven treadmill walking? MethodsEighteen subjects (10 M, 8 F; 62 ± 12 years; 1.73 ± 0.12 m; 84.9 ± 12.9 kg; 40 ± 30 months post-stroke) with chronic post-stroke hemiparesis participated in this study. Participants walked on an instrumented treadmill in its fixed-speed and user-driven modes at their self-selected and fastest comfortable walking speeds. Subjects wore retroreflective markers for motion capture. Shapiro-Wilk tests were used to assess for normality and one-way repeated measures ANOVAs were used to compare between conditions with α = 0.05. Bonferroni corrections were used for multiple comparisons. ResultsStep width was significantly smaller with user-driven control (13.7 cm, 95 % CI: [0.131, 0.145]) than fixed-speed control (16.8 cm, 95 % CI:[0.160, 0.174]), while step length and step time did not differ across treadmill conditions. Step length and step time differed between self-selected and fast walking speeds, but not treadmill control conditions. SignificanceThe results of this study show that user-driven treadmill control encourages healthy gait biomechanics and a greater sense of stability in post-stroke subjects. Individuals post-stroke walked with smaller step width with user-driven treadmill control, which has been associated with increased balance. Post-stroke gait rehabilitation may benefit from programs with user-driven treadmill training paradigms to improve mobility following stroke.

A Model-Based Analysis of Supraspinal Mechanisms of Inter-Leg Coordination in Human Gait: Toward Model-Informed Robot-Assisted Rehabilitation.

Stroke survivors are often left suffering from gait instability due to hemiparesis. This gait dysfunction can lead to higher fall rates and an overall decrease in quality of life. Though there are many post-stroke gait rehabilitation methods in use currently, none of them allow patients to regain complete functionality. Interlimb coordination is one of the main mechanisms of walking and is usually overlooked in most post-stroke gait rehabilitation protocols. This work attempts to help further understand the mechanism of interlimb coordination and how the brain is involved in it, studying the contralateral response to unilateral stiffness perturbations. A unique robotic device, the Variable Stiffness Treadmill (VST), is used in conjunction with a pre-established neuromuscular gait model to analyze for the first time the supraspinal control mechanisms involved in inter-leg coordination induced after unilateral perturbations. The attempt to explain the observed kinematic and muscular activation data via the gait model results in the identification of two control variables that seem to play an important role in gait stability and recovery after perturbations: the target angle of attack and target hip to ankle span. This is significant because these two parameters are directly related to longer stride length and larger foot clearance during swing phase. Both variables work toward correcting common issues with hemiparetic gait, such as a shorter stride and toe drag during swing phase of the paretic leg. The results of this work could aid in the design of future model-based stroke rehabilitation methods that would perturb the subject in a systematic way and allow targeted interventions with specific functional outcomes on gait. Additionally, this work-along with future studies-could assist in improving controllers for robust bipedal robots as well as our understanding of how the brain controls balance during perturbed walking.

Use of Vibrotactile Bracelets to Study Effects of Arm Swing Variation on Overground Gait

The high portability of vibrotactile feedback systems makes them suited to wearable applications, which improves their usability for rehabilitation applications encompassing a variety of environments and scenarios. A number of works have explored the relationship between arm movement and gait parameters such as gait variations and age on the arm swing. However, the inter-limb coupling scheme, i.e. the effects of the specific side (left or right) and direction (forward or backward) of arm swing variation on gait and balance parameters have not yet been evaluated. The study of these effects can enable us to devise arm movement based gait training protocols that may be beneficial for stroke survivors. We have developed a vibrotactile biofeedback system worn on the upper limb for post-stroke gait rehabilitation training. Using this system, we have carried out a study with ten healthy subjects and one stroke survivor to determine the effects of arm swing variation on gait and balance parameters. The healthy subject experiments revealed that increase in arm swing significantly increases the stride length while bringing about a statistically non-significant increase in the gait velocity. The study also revealed that the protocols involving variation of forward arm swing appear to have greater efficacy in modifying the gait symmetry ratio. Furthermore, the variations in arm swing and the resulting gait modifications do not produce any significant difference in the balance parameters. The results from the pilot test with one stroke survivor also show that increasing the arm swing increases the stride length and velocity. These findings suggest that arm swing variation using vibrotactile bracelets has effects on gait parameters that may be utilized for gait training of stroke survivors.

Feasibility of Using Foot-Ground Clearance Biofeedback Training in Treadmill Walking for Post-Stroke Gait Rehabilitation.

Hemiplegic stroke often impairs gait and increases falls risk during rehabilitation. Tripping is the leading cause of falls, but the risk can be reduced by increasing vertical swing foot clearance, particularly at the mid-swing phase event, minimum foot clearance (MFC). Based on previous reports, real-time biofeedback training may increase MFC. Six post-stroke individuals undertook eight biofeedback training sessions over a month, in which an infrared marker attached to the front part of the shoe was tracked in real-time, showing vertical swing foot motion on a monitor installed in front of the subject during treadmill walking. A target increased MFC range was determined, and participants were instructed to control their MFC within the safe range. Gait assessment was conducted three times: Baseline, Post-training and one month from the final biofeedback training session. In addition to MFC, step length, step width, double support time and foot contact angle were measured. After biofeedback training, increased MFC with a trend of reduced step-to-step variability was observed. Correlation analysis revealed that MFC height of the unaffected limb had interlinks with step length and ankle angle. In contrast, for the affected limb, step width variability and MFC height were positively correlated. The current pilot-study suggested that biofeedback gait training may reduce tripping falls for post-stroke individuals.

Balance, Lateropulsion, and Gait Disorders in Subacute Stroke.

To test the hypothesis that impaired body orientation with respect to gravity (lateropulsion) would play a key role in poststroke balance and gait disorders. Cohort study of 220 individuals consecutively admitted to a neurorehabilitation ward after a first hemisphere stroke (DOBRAS cohort [Determinants of Balance Recovery After Stroke] 2012-2018, ClinicalTrials.gov: NCT03203109), with clinical data systematically collected at 1 month, then at discharge. Primary outcomes were balance and gait disorders, quantified by the Postural Assessment Scale for Stroke and the modified Fugl-Meyer Gait Assessment, to be explained by all deficits on day 30, including lateropulsion assessed with the Scale for Contraversive Pushing. Statistics comprised linear regression analysis, univariate and multivariate analyses, and receiver operating characteristic curves. Lateropulsion was frequent, especially after right hemisphere stroke (RHS, D30, 48%; discharge 24%), almost always in right-handers. Among all deficits, impaired body orientation (lateropulsion) had the most detrimental effect on balance and gait. After RHS, balance disorders were proportional to lateropulsion severity, which alone explained almost all balance disorders at initial assessment (90%; 95% confidence interval [CI] [86-94], p < 0.001) and at discharge (92%; 95% CI 89-95, p < 0.001) and also the greatest part of gait disorders at initial assessment (66%; 95% CI 56-77, p < 0.001) and at discharge (68%; 95% CI 57-78, p < 0.001). Lateropulsion is the primary factor altering poststroke balance and gait at the subacute stage and therefore should be systematically assessed. Poststroke balance and gait rehabilitation should incorporate techniques devoted to misorientation with respect to gravity.