Feasibility of overground exoskeleton gait training during inpatient rehabilitation after severe acquired brain injury

OBJECTIVE

To describe the safety, feasibility, and tolerability of overground exoskeleton gait training (OEGT) integrated into clinical practice for patients after severe acquired brain injury (ABI).

SETTING

Inpatient rehabilitation hospital.

PARTICIPANTS

Eligible patients with severe ABI met the following criteria: age > 18, medically stable, met exoskeleton frame limitations, and a score of ≤ 3 on the motor function portion of the Coma Recovery Scale - Revised (CRS-R). Presence of consciousness disorder was not exclusionary.

DESIGN

Prospective observational study.

MAIN MEASURES

Outcomes examined safety (adverse events), feasibility (session count and barriers to session completion), and tolerability of OEGT (session metrics and heart rate).

RESULTS

Ten patients with ABI completed 10.4 ± 4.8 OEGT sessions with no adverse events. Barriers to session completion included clinical focus on prioritized interventions. Sessions [median up time = 17 minutes, (IQR: 7); walk time = 13 minutes, (IQR: 9); step count = 243, (IQR: 161); device assist = 74, (IQR: 28.0)] were primarily spent in Very Light to Light heart rate intensities [89%, (IQR: 42%) and 9%, (IQR: 33%), respectively].

CONCLUSION

OEGT incorporated into the rehabilitation plan of care during inpatient rehabilitation after severe ABI was observed to be safe, feasible, and tolerable. However, intentional steps must be taken to facilitate patient safety.

A robot-based interception task to quantify upper limb impairments in proprioceptive and visual feedback after stroke

BACKGROUND

A key motor skill is the ability to rapidly interact with our dynamic environment. Humans can generate goal-directed motor actions in response to sensory stimulus within ~ 60-200ms. This ability can be impaired after stroke, but most clinical tools lack any measures of rapid feedback processing. Reaching tasks have been used as a framework to quantify impairments in generating motor corrections for individuals with stroke. However, reaching may be inadequate as an assessment tool as repeated reaching can be fatiguing for individuals with stroke. Further, reaching requires many trials to be completed including trials with and without disturbances, and thus, exacerbate fatigue. Here, we describe a novel robotic task to quantify rapid feedback processing in healthy controls and compare this performance with individuals with stroke to (more) efficiently identify impairments in rapid feedback processing.

METHODS

We assessed a cohort of healthy controls (n = 135) and individuals with stroke (n = 40; Mean 41 days from stroke) in the Fast Feedback Interception Task (FFIT) using the Kinarm Exoskeleton robot. Participants were instructed to intercept a circular white target moving towards them with their hand represented as a virtual paddle. On some trials, the arm could be physically perturbed, the target or paddle could abruptly change location, or the target could change colour requiring the individual to now avoid the target.

RESULTS

Most participants with stroke were impaired in reaction time (85%) and end-point accuracy (83%) in at least one of the task conditions, most commonly with target or paddle shifts. Of note, this impairment was also evident in most individuals with stroke when performing the task using their unaffected arm (75%). Comparison with upper limb clinical measures identified moderate correlations with the FFIT.

CONCLUSION

The FFIT was able to identify a high proportion of individuals with stroke as impaired in rapid feedback processing using either the affected or unaffected arms. The task allows many different types of feedback responses to be efficiently assessed in a short amount of time.

Overground Robotic Exoskeleton Training for Patients With Stroke on Walking-Related Outcomes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

This review aims to evaluate the effectiveness of solely overground robotic exoskeleton (RE) training or overground RE training with conventional rehabilitation in improving walking ability, speed, and endurance among patients with stroke.

DATA SOURCES

Nine databases, 5 trial registries, gray literature, specified journals, and reference lists from inception until December 27, 2021.

STUDY SELECTION

Randomized controlled trials adopting overground robotic exoskeleton training for patients with any phases of stroke on walking-related outcomes were included.

DATA EXTRACTION

Two independent reviewers extracted items and performed risk of bias using the Cochrane Risk of Bias tool 1 and certainty of evidence using the Grades of Recommendation Assessment, Development, and Evaluation.

DATA SYNTHESIS

Twenty trials involving 758 participants across 11 countries were included in this review. The overall effect of overground robotic exoskeletons on walking ability at postintervention (d=0.21; 95% confidence interval [CI], 0.01, 0.42; Z=2.02; P=.04) and follow-up (d=0.37; 95% CI, 0.03, 0.71; Z=2.12; P=.03) and walking speed at postintervention (d=0.23; 95% CI, 0.01, 0.46; Z=2.01; P=.04) showed significant improvement compared with conventional rehabilitation. Subgroup analyses suggested that RE training should combine with conventional rehabilitation. A preferable gait training regime is <4 times per week over ≥6 weeks for ≤30 minutes per session among patients with chronic stroke and ambulatory status of independent walkers before training. Meta-regression did not identify any effect of the covariates on the treatment effect. The majority of randomized controlled trials had small sample sizes, and the certainty of the evidence was very low.

CONCLUSION

Overground RE training may have a beneficial effect on walking ability and walking speed to complement conventional rehabilitation. Further large-scale and long-term, high-quality trials are recommended to enhance the quality of overground RE training and confirm its sustainability.

Utilization of overground exoskeleton gait training during inpatient rehabilitation: a descriptive analysis

BACKGROUND

Overground exoskeleton gait training (OEGT) after neurological injury is safe, feasible, and may yield positive outcomes. However, no recommendations exist for initiation, progression, or termination of OEGT. This retrospective study highlights the clinical use and decision-making of OEGT within the physical therapy plan of care for patients after neurological injury during inpatient rehabilitation.

METHODS

The records of patients admitted to inpatient rehabilitation after stroke, spinal cord injury, or traumatic brain injury who participated in at least one OEGT session were retrospectively reviewed. Session details were analyzed to illustrate progress and included: "up" time, "walk" time, step count, device assistance required for limb swing, and therapist-determined settings. Surveys were completed by therapists responsible for OEGT sessions to illuminate clinical decision-making.

RESULTS

On average, patients demonstrated progressive tolerance for OEGT over successive sessions as shown by increasing time upright and walking, step count, and decreased assistance required by the exoskeleton. Therapists place preference on using OEGT with patients with more functional dependency and assess feedback from the patient and device to determine when to change settings. OEGT is terminated when other gait methods yield higher step repetitions or intensities, or to prepare for discharge.

CONCLUSION

Our descriptive retrospective data suggests that patients after neurological injury may benefit from OEGT during inpatient rehabilitation. As no guidelines exist, therapists' clinical decisions are currently based on a combination of knowledge of motor recovery and experience. Future efforts should aim to develop evidence-based recommendations to facilitate functional recovery after neurological injury by leveraging OEGT.

Exoskeleton-based training improves walking independence in incomplete spinal cord injury patients: results from a randomized controlled trial

BACKGROUND

In recent years, ambulatory lower limb exoskeletons are being gradually introduced into the clinical practice to complement walking rehabilitation programs. However, the clinical evidence of the outcomes attained with these devices is still limited and nonconclusive. Furthermore, the user-to-robot adaptation mechanisms responsible for functional improvement are still not adequately unveiled. This study aimed to (1) assess the safety and feasibility of using the HANK exoskeleton for walking rehabilitation, and (2) investigate the effects on walking function after a training program with it.

METHODS

A randomized controlled trial was conducted including a cohort of 23 patients with less than 1 year since injury, neurological level of injury (C2-L4) and severity (American Spinal Cord Injury Association Impairment Scale [AIS] C or D). The intervention was comprised of 15 one-hour gait training sessions with lower limb exoskeleton HANK. Safety was assessed through monitoring of adverse events, and pain and fatigue through a Visual Analogue Scale. LEMS, WISCI-II, and SCIM-III scales were assessed, along with the 10MWT, 6MWT, and the TUG walking tests (see text for acronyms).

RESULTS

No major adverse events were reported. Participants in the intervention group (IG) reported 1.8 cm (SD 1.0) for pain and 3.8 (SD 1.7) for fatigue using the VAS. Statistically significant differences were observed for the WISCI-II for both the "group" factor (F = 16.75, p < 0.001) and "group-time" interactions (F = 8.87; p < 0.01). A post-hoc analysis revealed a statistically significant increase of 3.54 points (SD 2.65, p < 0.0001) after intervention for the IG but not in the CG (0.7 points, SD 1.49, p = 0.285). No statistical differences were observed between groups for the remaining variables.

CONCLUSIONS

The use of HANK exoskeleton in clinical settings is safe and well-tolerated by the patients. Patients receiving treatment with the exoskeleton improved their walking independence as measured by the WISCI-II after the treatment.

Using a robotic exoskeleton at home: An activity tolerance case study of a child with spinal muscular atrophy

PURPOSE

Spinal Muscular Atrophy (SMA) Type II is a neurodegenerative disease that leads to progressive muscle weakness. It prevents children from walking and affects their respiratory function and their activity tolerance, among other health problems. We aimed to assess the activity tolerance showed by a child with SMA using a pediatric gait exoskeleton at home when walking and performing activities.

DESIGN AND METHODS

This study presents the case of a 6-year-old boy with SMA Type II and respiratory failure who used a pediatric gait exoskeleton at home for a period of two months. A nursing assessment was done before and during the use of the device to evaluate the child's activity tolerance during the sessions. Nursing interviews, performance, vital signs, fatigue, field notes, and functional scales were analyzed.

RESULTS

The nursing assessment showed a good activity tolerance of the child. Performance using the device improved over time; vital signs did not vary significantly during the sessions; fatigue perception decreased over time; and the child reached a higher score on some functional outcomes.

CONCLUSIONS

A first step has been taken to evaluate the impact of exoskeleton technology in children with SMA Type II from the nursing point of view, exposing the potential of this technology for the care of children with neuromuscular diseases, and the need for more research on the topic.

PRACTICE IMPLICATIONS

The information in this study will be useful to nurses to know the effects of gait exoskeletons in pediatric care of children with neuromuscular diseases like SMA.

A unilateral robotic knee exoskeleton to assess the role of natural gait assistance in hemiparetic patients

Background

Hemiparetic gait is characterized by strong asymmetries that can severely affect the quality of life of stroke survivors. This type of asymmetry is due to motor deficits in the paretic leg and the resulting compensations in the nonparetic limb. In this study, we aimed to evaluate the effect of actively promoting gait symmetry in hemiparetic patients by assessing the behavior of both paretic and nonparetic lower limbs. This paper introduces the design and validation of the REFLEX prototype, a unilateral active knee–ankle–foot orthosis designed and developed to naturally assist the paretic limbs of hemiparetic patients during gait.

Methods

REFLEX uses an adaptive frequency oscillator to estimate the continuous gait phase of the nonparetic limb. Based on this estimation, the device synchronically assists the paretic leg following two different control strategies: (1) replicating the movement of the nonparetic leg or (2) inducing a healthy gait pattern for the paretic leg. Technical validation of the system was implemented on three healthy subjects, while the effect of the generated assistance was assessed in three stroke patients. The effects of this assistance were evaluated in terms of interlimb symmetry with respect to spatiotemporal gait parameters such as step length or time, as well as the similarity between the joint’s motion in both legs.

Results

Preliminary results proved the feasibility of the REFLEX prototype to assist gait by reinforcing symmetry. They also pointed out that the assistance of the paretic leg resulted in a decrease in the compensatory strategies developed by the nonparetic limb to achieve a functional gait. Notably, better results were attained when the assistance was provided according to a standard healthy pattern, which initially might suppose a lower symmetry but enabled a healthier evolution of the motion of the nonparetic limb.

Conclusions

This work presents the preliminary validation of the REFLEX prototype, a unilateral knee exoskeleton for gait assistance in hemiparetic patients. The experimental results indicate that assisting the paretic leg of a hemiparetic patient based on the movement of their nonparetic leg is a valuable strategy for reducing the compensatory mechanisms developed by the nonparetic limb.

Physiotherapy using a free-standing robotic exoskeleton for patients with spinal cord injury: a feasibility study

BACKGROUND

Evidence is emerging for the use of overground lower limb robotic exoskeletons in the rehabilitation of people with spinal cord injury (SCI), with suggested benefits for gait speed, bladder and bowel function, pain management and spasticity. To date, research has focused on devices that require the user to support themselves with a walking aid. This often precludes use by those with severe trunk, postural or upper limb deficits and places the user in a suboptimal, flexed standing position. Free-standing exoskeletons enable people with higher level injuries to exercise in an upright position. This study aimed to evaluate the feasibility of therapy with a free-standing exoskeleton for those with SCI, and to determine the potential health-related benefits of this intervention.

METHODS

This 12-week intervention study with 12-week waitlist control and 12-week follow up, provided people with SCI scoring < 5 on the mobility section of the spinal cord independence measure (SCIM-III) twice weekly therapy in the REX (Rex Bionics, Auckland, NZ), a free-standing lower limb robotic exoskeleton. The primary outcome measure of interest was function, as measured on the SCIM-III. A battery of secondary outcomes was included. Participants also completed a survey on their perceptions of this treatment modality, to determine acceptability.

RESULTS

Forty-one potential participants were screened for eligibility. Two females (one ASIA A, one ASIA C) and one male (ASIA B) completed all 24 intervention sessions, and the follow up assessment. One participant showed positive trends in function, fatigue, quality of life and mood during the intervention phase. Grip and quadriceps strength, and lower limb motor function improved in another. Two improved their percentage of lean body mass during the intervention phase. Remaining results were varied across patients, time points and outcomes. The intervention was highly acceptable to all participants.

CONCLUSION

With three of 41 potential participants being eligible and completing this study, our results show that there are potential benefits of exercise in a free-standing exoskeleton for people with severe mobility impairment due to SCI, for a small subset of patients. Further research is warranted to determine those most likely to benefit, and the type of benefit depending on the patient characteristics. Trial registration The trial was registered prospectively on 20 April 2018 at www.anzctr.org.au/ (ACTRN12618000626268).

The adjunct of transcranial direct current stimulation to Robot-assisted therapy in upper limb post-stroke treatment

Transcranial direct current stimulation (TDCS) and robot-assisted therapy (RAT) proved to be promising interventions in post-stroke rehabilitation. However, the effects of combining the two treatments are not significantly clear. To determine the effects of combined therapy using transcranial direct current stimulation (tDCS) with robot-assisted therapy (RAT) in the impairment of the upper limb in stroke rehabilitation. The Cochrane Library, MEDLINE, Embase, Google Scholar, and Trial Registries were systematically searched for randomised controlled trials in May 2020. As the outcome, the Fugl-Meyer Assessment score (FMS) was used. A pairwise and a network meta-analysis were performed. 5 RCTs with RAT versus RAT + tDCS groups and 21 RCTs with RAT versus the control group with 892 people were analysed. Of these studies, 10 RCTs evaluated acute-subacute (<8 weeks) people, while 16 chronic people. By analysing the FMS with a pair-wise meta-analysis, we demonstrate significant improvements only in the RAT alone compared to the control (acute-subacute, SMD:4.09 (1.31, 6.87) and chronic, SMD:2.22 (0.99, 3.45)). Instead, performing a network meta-analysis, through an analysis of the surface under the cumulative ranking curve (SUCRA) we report a ranking of the effectiveness of the interventions. We assess SUCRA in acute-subacute stroke: Control:0.23, RAT + tDCS:0.31, RAT:0.96 and in chronic stroke: Control:0.06, RAT + tDCS:0.62, RAT:0.82. RAT is, respectively, 96% and 82% likely to be the best-ranked treatment. Despite the limitations, this network meta-analysis appears to demonstrate through the rank of interventions that adding tDCS to RAT is not useful in upper-limb stroke rehabilitation.

Evidence of neuroplasticity with robotic hand exoskeleton for post-stroke rehabilitation: a randomized controlled trial

Background

A novel electromechanical robotic-exoskeleton was designed in-house for the rehabilitation of wrist joint and Metacarpophalangeal (MCP) joint.

Objective

The objective was to compare the rehabilitation effectiveness (clinical-scales and neurophysiological-measures) of robotic-therapy training sessions with dose-matched conventional therapy in patients with stroke.

Methods

A pilot prospective parallel randomized controlled study at clinical settings was designed for patients with stroke within 2 years of chronicity. Patients were randomly assigned to receive an intervention of 20 sessions of 45 min each, five days a week for four weeks, in Robotic-therapy Group (RG) (n = 12) and conventional upper-limb rehabilitation in Control-Group (CG) (n = 11). We intended to evaluate the effects of a novel exoskeleton based therapy on the functional rehabilitation outcomes of upper-limb and cortical-excitability in patients with stroke as compared to the conventional-rehabilitation. Clinical-scales– Modified Ashworth Scale, Active Range of Motion, Barthel-Index, Brunnstrom-stage and Fugl-Meyer (FM) scale and neurophysiological measures of cortical-excitability (using Transcranial Magnetic Stimulation) –Motor Evoked Potential and Resting Motor threshold, were acquired pre- and post-therapy.

Results

No side effects were noticed in any of the patients. Both RG and CG showed significant (p < 0.05) improvement in all clinical motor-outcomes except Modified Ashworth Scale in CG. RG showed significantly (p < 0.05) higher improvement over CG in Modified Ashworth Scale, Active Range of Motion and Fugl-Meyer scale and FM Wrist-/Hand component. An increase in cortical-excitability in ipsilesional-hemisphere was found to be statistically significant (p < 0.05) in RG over CG, as indexed by a decrease in Resting Motor Threshold and increase in the amplitude of Motor Evoked Potential. No significant changes were shown by the contralesional-hemisphere. Interhemispheric RMT-asymmetry evidenced significant (p < 0.05) changes in RG over CG indicating increased cortical-excitability in ipsilesional-hemisphere along with interhemispheric changes.

Conclusion

Robotic-exoskeleton training showed improvement in motor outcomes and cortical-excitability in patients with stroke. Neurophysiological changes in RG could most likely be a consequence of plastic reorganization and use-dependent plasticity.

Trial registry number: ISRCTN95291802

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00867-7.

A pilot randomized controlled trial of robotic exoskeleton-assisted exercise rehabilitation in multiple sclerosis

BACKGROUND

Co-occurring mobility and cognitive impairments are common, debilitating, and poorly-managed with pharmacological therapies in persons with multiple sclerosis (MS). Exercise rehabilitation (ER), particularly walking ER, has been suggested as one of the best approaches for managing these manifestations of MS. However, there is a focal lack of efficacy of ER on mobility and cognitive outcomes in persons with MS who present with substantial neurological disability. Such severe neurological disability oftentimes precludes the ability for participation in highly-intensive and repetitive ER that is necessary for eliciting adaptations in mobility and cognition. To address such a concern, robotic exoskeleton-assisted ER (REAER) might represent a promising intervention approach for managing co-occurring mobility and cognitive impairments in those with substantial MS disability who might not benefit from traditional ER.

METHODS

The current pilot single-blind, randomized controlled trial (RCT) compared the effects of 4-weeks of REAER with 4-weeks of conventional gait training (CGT) as a standard-of-care control condition on functional mobility (timed up-and-go; TUG), walking endurance (six-minute walk test; 6MWT), cognitive processing speed (CPS; Symbol Digit Modalities Test; SDMT), and brain connectivity (thalamocortical resting-state functional connectivity (RSFC) based on fMRI) outcomes in 10 persons with substantial MS-related neurological disability.

RESULTS

Overall, compared with CGT, 4-weeks of REAER was associated with large improvements in functional mobility (η_p²=.38), CPS (η_p²=.53), and RSFC between the thalamus and ventromedial prefrontal cortex (η_p²=.72), but not walking endurance (η_p²=.01). Further, changes in RSFC were moderately associated with changes in TUG, 6MWT, and SDMT performance, respectively, whereby increased thalamocortical RSFC was associated with improved functional mobility, walking endurance, and CPS (|ρ|>.36).

CONCLUSION

The current pilot RCT provides initial support for REAER as an approach for improving functional mobility and CPS, perhaps based on adaptive and integrative central nervous system plasticity, namely increases in RSFC between the thalamus and ventromedial prefrontal cortex, in a small sample of persons with substantial MS disability. Such a pilot trial provides proof-of-concept data for the design and implementation of an appropriately-powered RCT of REAER in a larger sample of persons with MS who present with co-occurring impairments in both mobility and cognitive functioning.

Wearable rehabilitation exoskeletons of the lower limb: analysis of versatility and adaptability

PURPOSE

To analyse the versatility and adaptability of commercially available exoskeletons for mobility assistance and their adaptation to diverse pathologies through a review of clinical trials in robotic lower limb training.

DATA SOURCES

A computer-aided search in bibliographic databases (PubMed and Web of Science) of clinical trials published up to September 2020 was done.

METHODS

To be selected for detailed review, clinical trials had to meet the following criteria: (1) a protocol was designed and approved, (2) participants were people with pathologies, and (3) the trials were not a single case study. Clinical trial data were collected, extracted, and analysed, considering: objectives, trial participants, number of sessions, pathologies involved, and conclusions.

RESULTS

The search resulted in 312 potentially relevant studies of seven commercial exoskeletons, of which 135 passed the preliminary screening; and 69 studies were finally selected. Of the 69 clinical trials included in the review about 50% involved Spinal Cord Injury participants, while roughly 25% focussed on stroke and two trials corresponded to patients with both disorders. The rest were composed of neurological diseases and trauma disorders.

CONCLUSIONS

The use of a single wearable robot for different medical conditions in various diseases is a challenge. Based on this comparative, the properties of the exoskeletons that improve the working ability with different pathologies and patient conditions have been evaluated. Suggestions were made for developing a new lower-limb exoskeleton based on various modules with a distributed control system to improve versatility in wearable technology for different gait pattern progression.Implications for rehabilitationWearable robotic exoskeletons for gait assistance have been analysed from the perspective of adaptation to different diseases.This paper emphasizes the importance of personalized therapies and adaptive assistive technology.Suggestions were made for a new modular exoskeleton capable of addressing the issue of low versatility characterizing currently wearable assistive technology.

A biomechanical comparison of powered robotic exoskeleton gait with normal and slow walking: An investigation with able-bodied individuals

BACKGROUND

Overground lower-limb robotic exoskeletons are assistive devices used to facilitate ambulation and gait rehabilitation. Our understanding of how closely they resemble comfortable and slow walking is limited. This information is important to maximise the effects of gait rehabilitation. The aim was to compare the 3D gait parameters of able-bodied individuals walking with and without an exoskeleton at two speeds (self-selected comfortable vs. slow, speed-matched to the exoskeleton) to understand how the user's body moved within the device.

METHODS

Eight healthy, able-bodied individuals walked along a 12-m walkway with and without the exoskeleton. Three-dimensional whole-body kinematics inside the device were captured. Temporal-spatial parameters and sagittal joint kinematics were determined for normal and exoskeleton walking. One-way repeated measures ANOVAs and statistical parametric mapping were used to compare the three walking conditions (P < .05).

FINDINGS

The walking speeds of the slow (0.44[0.03] m/s) and exoskeleton (0.41[0.03] m/s) conditions were significantly slower than the comfortable walking speed (1.54[0.07] m/s). However, time in swing was significantly greater (P < .001, d = -3.64) and double support was correspondingly lower (P < .001, d = 3.72) during exoskeleton gait than slow walking, more closely resembling comfortable speed walking. Ankle and knee angles were significantly reduced in the slow and exoskeleton conditions. Angles were also significantly different for the upper body.

INTERPRETATION

Although the slow condition was speed-matched to exoskeleton gait, the stance:swing ratio of exoskeleton stepping more closely resembled comfortable gait than slow gait. The altered upper body kinematics suggested that overground exoskeletons may provide a training environment that would also benefit balance training.

The feasibility of assessing cognitive and motor function in multiple sclerosis patients using robotics

Background

Multiple sclerosis (MS) causes pervasive motor, sensory and cognitive dysfunction. The Expanded Disability Status Scale (EDSS) is the gold standard for assessing MS disability. The EDSS is biased towards mobility and may not accurately measure MS-related disabilities in the upper limb or in cognitive functions (e.g. executive function).

Objective

Our objectives were to determine the feasibility of using the Kinarm robotic system to quantify neurological deficits related to arm function and cognition in MS patients, and examine relationships between traditional clinical assessments and Kinarm variables.

Methods

Individuals with MS performed 8 robotic tasks assessing motor, cognitive, and sensory ability. We additionally collected traditional clinical assessments and compared these to the results of the robotic assessment.

Results

Forty-three people with MS were assessed. Most participants could complete the robotic assessment. Twenty-six (60%) were impaired on at least one cognitive task and twenty-six (60%) were impaired on at least one upper-limb motor task. Cognitive domain task performance correlated most strongly with the EDSS.

Conclusions

Kinarm robotic assessment of people with MS is feasible, can identify a broad range of upper-limb motor and sensory, as well as cognitive, impairments, and complements current clinical rating scales in the assessment of MS-related disability.

Voluntary control of wearable robotic exoskeletons by patients with paresis via neuromechanical modeling

BACKGROUND

Research efforts in neurorehabilitation technologies have been directed towards creating robotic exoskeletons to restore motor function in impaired individuals. However, despite advances in mechatronics and bioelectrical signal processing, current robotic exoskeletons have had only modest clinical impact. A major limitation is the inability to enable exoskeleton voluntary control in neurologically impaired individuals. This hinders the possibility of optimally inducing the activity-driven neuroplastic changes that are required for recovery.

METHODS

We have developed a patient-specific computational model of the human musculoskeletal system controlled via neural surrogates, i.e., electromyography-derived neural activations to muscles. The electromyography-driven musculoskeletal model was synthesized into a human-machine interface (HMI) that enabled poststroke and incomplete spinal cord injury patients to voluntarily control multiple joints in a multifunctional robotic exoskeleton in real time.

RESULTS

We demonstrated patients' control accuracy across a wide range of lower-extremity motor tasks. Remarkably, an increased level of exoskeleton assistance always resulted in a reduction in both amplitude and variability in muscle activations as well as in the mechanical moments required to perform a motor task. Since small discrepancies in onset time between human limb movement and that of the parallel exoskeleton would potentially increase human neuromuscular effort, these results demonstrate that the developed HMI precisely synchronizes the device actuation with residual voluntary muscle contraction capacity in neurologically impaired patients.

CONCLUSIONS

Continuous voluntary control of robotic exoskeletons (i.e. event-free and task-independent) has never been demonstrated before in populations with paretic and spastic-like muscle activity, such as those investigated in this study. Our proposed methodology may open new avenues for harnessing residual neuromuscular function in neurologically impaired individuals via symbiotic wearable robots.

Effects of an over-ground exoskeleton on external knee moments during stance phase of gait in healthy adults

BACKGROUND

Physical activity and exercise is central to conservative management of knee osteoarthritis (KOA), but is often difficult for patients with KOA to maintain over the decade or more prior to surgical management. Better approaches are needed for maintaining physical function and health in this population that can also address the patho-biomechanics of the osteoarthritic knee. The objective of the study is to quantify how a lower-extremity robotic exoskeleton (dermoskeleton) modifies the external knee moments during over-ground walking in a sample of healthy adults, and to evaluate these biomechanical modifications in the context of the osteoarthritic knee.

METHOD

Motion analysis data was acquired for 13 participants walking with and without the dermoskeleton. Force plate data, external knee moment arms, and knee moments in the laboratory and tibia frames of reference were computed, as well as time-distance parameters of walking, and compared between the two conditions.

RESULTS

Although gait speed was not different, users took shorter and wider steps when walking with the dermoskeleton. Ground reaction forces and early-stance knee moment increased due to the added mass of the dermoskeleton, but the knee adduction moment was significantly reduced in late stance phase of gait. There was no effect on the knee torsional moment when measured in the anatomical frame of reference, and the late-stance knee flexion moment was invariant.

CONCLUSIONS

The dermoskeleton demonstrated favorable biomechanical modifications at the knee in healthy adults while walking. Studies are warranted to explore this technology for enabling physical activity-based interventions in patients with KOA.

Robotic Assist-As-Needed as an Alternative to Therapist-Assisted Gait Rehabilitation

OBJECTIVE

Body Weight Supported Treadmill Training (BWSTT) with therapists' assistance is often used for gait rehabilitation post-stroke. However, this training method is labor-intensive, requiring at least one or as many as three therapists at once for manual assistance. Previously, we demonstrated that providing movement guidance using a performance-based robot-aided gait training (RAGT) that applies a compliant, assist-as-needed force-field improves gait pattern and functional walking ability in people post-stroke. In the current study, we compared the effects of assist-as-needed RAGT combined with functional electrical stimulation and visual feedback with BWSTT to determine if RAGT could serve as an alternative for locomotor training.

METHODS

Twelve stroke survivors were randomly assigned to one of the two groups, either receiving BWSTT with manual assistance or RAGT with functional electrical stimulation and visual feedback. All subjects received fifteen 40-minutes training sessions.

RESULTS

Clinical measures, kinematic data, and EMG data were collected before and immediately after the training for fifteen sessions. Subjects receiving RAGT demonstrated significant improvements in their self-selected over-ground walking speed, Functional Gait Assessment, Timed Up and Go scores, swing-phase peak knee flexion angle, and muscle coordination pattern. Subjects receiving BWSTT demonstrated significant improvements in the Six-minute walk test. However, there was an overall trend toward improvement in most measures with both interventions, thus there were no significant between-group differences in the improvements following training.

CONCLUSION

The current findings suggest that RAGT worked at least as well as BWSTT and thus may be used as an alternative rehabilitation method to improve gait pattern post-stroke as it requires less physical effort from the therapists compared to BWSTT.

Powered robotic exoskeletons in post-stroke rehabilitation of gait: a scoping review

Powered robotic exoskeletons are a potential intervention for gait rehabilitation in stroke to enable repetitive walking practice to maximize neural recovery. As this is a relatively new technology for stroke, a scoping review can help guide current research and propose recommendations for advancing the research development. The aim of this scoping review was to map the current literature surrounding the use of robotic exoskeletons for gait rehabilitation in adults post-stroke. Five databases (Pubmed, OVID MEDLINE, CINAHL, Embase, Cochrane Central Register of Clinical Trials) were searched for articles from inception to October 2015. Reference lists of included articles were reviewed to identify additional studies. Articles were included if they utilized a robotic exoskeleton as a gait training intervention for adult stroke survivors and reported walking outcome measures. Of 441 records identified, 11 studies, all published within the last five years, involving 216 participants met the inclusion criteria. The study designs ranged from pre-post clinical studies (n = 7) to controlled trials (n = 4); five of the studies utilized a robotic exoskeleton device unilaterally, while six used a bilateral design. Participants ranged from sub-acute (<7 weeks) to chronic (>6 months) stroke. Training periods ranged from single-session to 8-week interventions. Main walking outcome measures were gait speed, Timed Up and Go, 6-min Walk Test, and the Functional Ambulation Category. Meaningful improvement with exoskeleton-based gait training was more apparent in sub-acute stroke compared to chronic stroke. Two of the four controlled trials showed no greater improvement in any walking outcomes compared to a control group in chronic stroke. In conclusion, clinical trials demonstrate that powered robotic exoskeletons can be used safely as a gait training intervention for stroke. Preliminary findings suggest that exoskeletal gait training is equivalent to traditional therapy for chronic stroke patients, while sub-acute patients may experience added benefit from exoskeletal gait training. Efforts should be invested in designing rigorous, appropriately powered controlled trials before powered exoskeletons can be translated into a clinical tool for gait rehabilitation post-stroke.

The embodiment of assistive devices-from wheelchair to exoskeleton

Spinal cord injuries (SCIs) place a heavy burden on the healthcare system and have a high personal impact and marked socio-economic consequences. Clinically, no absolute cure for these conditions exists. However, in recent years, there has been an increased focus on new robotic technologies that can change the frame we think about the prognosis for recovery and for treating some functions of the body affected after SCIs. This review has two goals. The first is to assess the possibility of the embodiment of functional assistive tools after traumatic disruption of the neural pathways between the brain and the body. To this end, we will examine how altered sensorimotor information modulates the sense of the body in SCI. The second goal is to map the phenomenological experience of using external tools that typically extend the potential of the body physically impaired by SCI. More specifically, we will focus on the difference between the perception of one's physically augmented and non-augmented affected body based on observable and measurable behaviors. We discuss potential clinical benefits of enhanced embodiment of the external objects by way of multisensory interventions. This review argues that the future evolution of human robotic technologies will require adopting an embodied approach, taking advantage of brain plasticity to allow bionic limbs to be mapped within the neural circuits of physically impaired individuals.