Posts Tagged Exoskeleton
[Abstract] Lessons learned from robotic gait training during rehabilitation: Therapeutic and medical severity considerations over 3 years
BACKGROUND: Robotic exoskeletons are increasingly available to inpatient rehabilitation facilities though programmatic implementation evidence is limited.
OBJECTIVE: To describe therapists’ clinical practice experiences with robotic gait training (RGT) over 3 years during inpatient rehabilitation.
METHODS: Therapists participated in a survey and semi-structured focus group to discuss their RGT experiences. Interviews were recorded, transcribed, and analyzed using a theoretical analysis-driven thematic approach.
RESULTS: Therapists averaged 7.6 years of neurologic rehabilitation experience and 1.85 years with RGT. Eight of 10 therapists had completed ⩾ 50 RGT sessions, with frequency of 1–5 sessions/week, including on-label (spinal cord injury, stroke) and off-label (e.g., traumatic brain injury) experiences. Three adverse events occurred over 716 RGT sessions with 186 patients. Qualitative analysis identified three major themes and corresponding subthemes: 1-Comparison with traditional gait training approaches (6 sub-themes), 2-Clinical decision-making considerations (3), and 3-On-label and off-label utilization (4). Stated RGT benefits included decreased therapists’ physical burden and increased patient motivation. Clinical concerns with RGT included tonicity, continence, and patient communication (e.g., aphasia). Off-label RGT was used to overcome barriers in traditional gait therapy and achieve early mobility.
CONCLUSIONS: Therapists’ level of training and clinical knowledge furthered RGT implementation and allowed for safe utilization with on-label and off-label patients.
[Abstract + References] Kineto-static Analysis of a Compact Wrist Rehabilitation Robot Including the Effect of Human Soft Tissue to Compensate for Joint Misalignment
Developing a simple, comfortable rehabilitation robot that can carry out in-home rehabilitation has been a long-time challenge. In this paper, we present a rehabilitation robot with one degree of freedom (DOF) for wrist joint flexion-extension movement. Passive joints have been added to the exoskeleton, forming a four-bar slider crank mechanism, which can reduce unwanted forces due to joint misalignment. A concept of modeling human soft tissue as a passive prismatic joint with spring is introduced in order to achieve the compactness and comfort of the robot simultaneously. In addition, the effects of human soft tissue displacement are compared. A trade-off between robot volume and comfort is discussed. Finally, the kineto-static analysis of the proposed design is conducted to prove the feasibility of adopting this concept in robot-assisted rehabilitation.
- 1.Maciejasz, P., Eschweiler, J., Gerlach-Hahn, K., Jansen-Troy, A., Leonhardt, S.: A survey on robotic devices for upper limb rehabilitation. J. Neuroeng. Rehabil. 11(1), 3–31 (2014)CrossRefGoogle Scholar
- 2.Norouzi-Gheidari, N., Archambault, P.S., Fung, J.: Effects of robot-assisted therapy on stroke rehabilitation in upper limbs: Systematic review and meta-analysis of the literature. J. Rehabil. Res. Dev. 49(4), 479–496 (2012)CrossRefGoogle Scholar
- 3.Ryu, J., Cooney, W.P., Askew, L.J., An, K.-N., Chao, E.Y.S.: Functional ranges of motion of the wrist joint. J. Hand Surg. Am. 16(3), 409–419 (1991)CrossRefGoogle Scholar
- 4.Pezent, E., Rose, C.G., Deshpande, A.D., O’Malley, M.K.: Design and characterization of the openwrist: A robotic wrist exoskeleton for coordinated hand-wrist rehabilitation. In: 2017 International Conference on Rehabilitation Robotics (ICORR), pp. 720–725 (2017)Google Scholar
- 5.McDaid, A.J.: Development of an Anatomical Wrist Therapy Exoskeleton (AW-TEx). In: 2015 IEEE International Conference on Rehabilitation Robotics (ICORR), pp. 434–439 (2015)Google Scholar
- 6.Singh, N., Saini, M., Anand, S., Kumar, N., Srivastava, M.V.P., Mehndiratta, A.: Robotic exoskeleton for wrist and fingers joint in post-stroke neuro-rehabilitation for low-resource settings. IEEE Trans. Neural Syst. Rehabil. Eng. 27(12), 2369–2377 (2019)CrossRefGoogle Scholar
- 7.Näf, M.B., Junius, K., Rossini, M., Rodriguez-Guerrero, C., Vanderborght, B., Lefeber, D.: Misalignment compensation for full human-exoskeleton kinematic compatibility: State of the art and evaluation. Appl. Mech. Rev. 70(5), 1–19 (2019)Google Scholar
- 8.Liu, Y.-C., Takeda, Y.: Static analysis of a wrist rehabilitation robot with consideration to the compliance and joint misalignment between the robot and human hand. In: Proceedings of Annual Conference of the Robotics Society of Japan 2019, Tokyo (2019)Google Scholar
- 9.Liu, Y.-C., Takeda, Y.: Kineto-static analysis of a wrist rehabilitation robot with compliant elements and supplementary passive joints to compensate the joint misalignment. In: The 25th Jc-IFToMM Symposium, Japan (2019)Google Scholar
- 10.Xiao, Z.G., Menon, C.: Towards the development of a portable wrist exoskeleton. In: 2011 IEEE International Conference on Robotics and Biomimetics, pp. 1884–1889 (2011)Google Scholar
- 11.Takeda, Y., Sugahara, Y., Matsuura, D., Matsuda, S., Suzuki, T., Kitagawa, M., Liu, Y.-C.: Introduction of dynamic pair to modeling and kinemato-dynamic analysis of wearable assist-devices. In: The JSME Annual Mechnical Engineering Congress 2019, Akita, Japan (2019)Google Scholar
- 12.Yu, T.F., Wilson, A.J.: A passive movement method for parameter estimation of a musculo-skeletal arm model incorporating a modified hill muscle model. Comput. Methods Programs Biomed. 114(3), e46–e59 (2014)CrossRefGoogle Scholar
September 14, 2020 By Annette Boyle
B-Temia Inc.’s Keeogo mobility device is on the move in the U.S. now that it has received 510(k) clearance from the U.S. FDA. Unlike currently available exoskeletons that move for patients, the Keeogo (keep on going) Dermoskeleton system amplifies signals from patients who can initiate movement but need additional assistance.
“This U.S. market clearance is the biggest milestone of our global regulatory expansion, as the USA is the largest medical device market. It also gives us great confidence for the other regulatory approvals we are currently completing for additional territories,” said B-Temia’s president and CEO Stéphane Bédard.
The U.S. action specifically covers use of the device for stroke patients in rehabilitation settings. “Stroke is just the entry door,” Bédard told BioWorld. “We want to extend U.S. authorization for other indications in the future. We’ve done very well for stroke patients and want to do the same for those with multiple sclerosis, osteoarthritis of the knee, Parkinson’s disease, and partial spinal cord injuries.”
The company also hopes to gain clearance for patients to use the device on a day-to-day basis, not just during rehab sessions. “Keeogo has as its main purpose providing the person the ability to regain their activity on a daily basis walking, shopping, out in the yard. That’s why we invented it,” Bédard added. “We will reach that level in the U.S., but with the FDA, you have to go step-by-step for each indication.”
Keeogo already has much broader authorization in Europe where it received CE mark authorization in December 2019. In the 28 European countries covered by the CE mark, Quebec-based B-Temia can market the system to provide additional strength and stability to users with musculoskeletal weakness or lower limb instability both at home and in clinics. The system has been approved by Health Canada since 2015 for a range of indications as well.
Keeogo is a lightweight motorized walking assistive device that boosts leg power. Its dermoskeleton technology employs artificial intelligence (AI) to help individuals with impaired mobility walk, run, sit, and climb. Underpinned by a model of human biomechanics and the basics elements of gait, the AI uses additional mathematical equations to intervene properly in the movement.
The AI, housed on a belt worn at the waist, interprets information transmitted by sensors strapped to the leg to understand the user’s intent and then provides the compensation needed so they can achieve their goal. It is unique in that it does not replace an individual’s motion, only augments it. “If you don’t walk, it won’t move,” said Bédard. “It will add its response to your own characteristic speed and cadence and is fully customizable to the specifics of a disease and person. We’re only able to achieve this level of sophistication with AI.”
By augmenting the user’s motions, Keeogo works to help them regain or retain their autonomy and mobility. “When you go in the lab with Keeogo, you extend your range of motion, augment stride length, and increase the biomechanical ability to walk,” explained Bédard. “When you repeat recursive exercises, you build your capacity. You extend what you’ve done in the past– the body has a memory of that – and Keeogo synchronizes the motions, extends the gait, so that day after day you regain capacity.” In Parkinson’s and other degenerative diseases, the system helps patients hold onto their independence and not fall into a pattern of doing less and less as the disease progresses and movement becomes more challenging.
Notably, the system is not tied to an idealized motion. “We’re not trying to perfect the individual’s gait, just to improve it. We want to keep the individual’s natural gait. They will improve themselves as they use the system,” Bédard said.
Aside from its clinical applications, B-Temia also continues to develop its military version of Keeogo, the Onyx exoskeleton, for the U.S. Army. It has worked with Lockheed Martin since 2017 to support soldiers tasked with carrying loads of more than 100 pounds. Under that weight, people naturally change their gait. In addition, the weight puts such pressure on the joints that it often leads to both acute and chronic musculoskeletal injuries.
“The approval also confers additional credibility for the corporation that will open a lot of doors in terms of investors, financing, and partnerships,” Bédard said.
He plans to spend the next several weeks determining how to execute properly on commercialization in the U.S. and elsewhere so that the device can be easily acquired by individuals who could benefit. “Our next challenge is to establish a good strategy. There are many options on the table and we want to make sure we choose the right structure, partners and channels.
[Abstract] Implementing the exoskeleton Ekso GTTM for gait rehabilitation in a stroke unit – feasibility, functional benefits and patient experiences
Reports on the implementation of exoskeletons for gait rehabilitation in clinical settings are limited.
How feasible is the introduction of exoskeleton gait training for patients with subacute stroke in a specialized rehabilitation hospital?
What are the functional benefits and the patient experiences with training in the Ekso GTTM exoskeleton?
During an 18 months inclusion period, 255 in-patients were screened for eligibility. Inclusion criteria were; walking difficulties, able to stand 10 min in a standing frame, fitting into the robot and able to cooperate. One-hour training sessions 2–3 times per week for approximately 3 weeks were applied as a part of the patients’ ordinary rehabilitation programme. Assessments: Functional Independence Measure, Motor Assessment Scale (MAS), Ekso GTTM walking data, patient satisfaction and perceived exertion of the training sessions (Borg scale).
Two physiotherapists were certified at the highest level of Ekso GTTM. Twenty-six patients, median age 54 years, were included. 177 training sessions were performed. Statistical significant changes were found in MAS total score (p < 0.003) and in the gait variables walking time, up-time, and a number of steps (p < 0.001). Patients reported fairly light perceived exertion and a high level of satisfaction and usefulness with the training sessions. Few disadvantages were reported. Most patients would like to repeat this training if offered.
Ekso GTTM can safely be implemented as a training tool in ordinary rehabilitation under the prerequisite of a structured organization and certified personnel. The patients progressed in all outcome measures and reported a high level of satisfaction.
- Implications for rehabilitation
- The powered exoskeleton Ekso GTTM was found feasible as a training option for in-patients with severe gait disorders after stroke within an ordinary rehabilitation setting.
- The Ekso GTTM must be operated by a certified physiotherapist, and sufficient assistive personnel must be available for safe implementation.
- Patients’ perceived exertion when training in the Ekso GTTM was relatively low.
- The patients expressed satisfaction with this training option.
[Abstract + Similar articles] Adapting to the Mechanical Properties and Active Force of an Exoskeleton by Altering Muscle Synergies in Chronic Stroke Survivors
Chronic stroke survivors often suffer from gait impairment resistant to intervention. Recent rehabilitation strategies based on gait training with powered exoskeleton appear promising, but whether chronic survivors may benefit from them remains controversial. We evaluated the potential of exoskeletal gait training in restoring normal motor outputs in chronic survivors (N=10) by recording electromyographic signals (EMGs, 28 muscles both legs) as they adapted to exoskeletal perturbations, and examined whether any EMG alterations after adaptation were underpinned by closer-to-normal muscle synergies. A unilateral ankle-foot orthosis that produced dorsiflexor torque on the paretic leg during swing was tested. Over a single session, subjects walked overground without exoskeleton (FREE), then with the unpowered exoskeleton (OFF), and finally with the powered exoskeleton (ON). Muscle synergies were identified from EMGs using non-negative matrix factorization. During adaptation to OFF, some paretic-side synergies became more dissimilar to their nonparetic-side counterparts. During adaptation to ON, in half of the subjects some paretic-side synergies became closer to their nonparetic references relative to their similarity at FREE as these paretic-side synergies became sparser in muscle components. Across subjects, level of inter-side similarity increase correlated negatively with the degree of gait temporal asymmetry at FREE. Our results demonstrate the possibility that for some survivors, exoskeletal training may promote closer-to-normal muscle synergies. But to fully achieve this, the active force must trigger adaptive processes that offset any undesired synergy changes arising from adaptation to the device’s mechanical properties while also fostering the reemergence of the normal synergies.
- Motor modules during adaptation to walking in a powered ankle exoskeleton.Jacobs DA, Koller JR, Steele KM, Ferris DP.J Neuroeng Rehabil. 2018 Jan 3;15(1):2. doi: 10.1186/s12984-017-0343-x.PMID: 29298705 Free PMC article.
- Changes in leg cycling muscle synergies after training augmented by functional electrical stimulation in subacute stroke survivors: a pilot study.Ambrosini E, Parati M, Peri E, De Marchis C, Nava C, Pedrocchi A, Ferriero G, Ferrante S.J Neuroeng Rehabil. 2020 Feb 27;17(1):35. doi: 10.1186/s12984-020-00662-w.PMID: 32106874 Free PMC article.
- A neuromechanics-based powered ankle exoskeleton to assist walking post-stroke: a feasibility study.Takahashi KZ, Lewek MD, Sawicki GS.J Neuroeng Rehabil. 2015 Feb 25;12:23. doi: 10.1186/s12984-015-0015-7.PMID: 25889283 Free PMC article.
- Contributions to the understanding of gait control.Simonsen EB.Dan Med J. 2014 Apr;61(4):B4823.PMID: 24814597 Review.
- Powered robotic exoskeletons in post-stroke rehabilitation of gait: a scoping review.Louie DR, Eng JJ.J Neuroeng Rehabil. 2016 Jun 8;13(1):53. doi: 10.1186/s12984-016-0162-5.PMID: 27278136 Free PMC article. Review.
[ARTICLE] Walking with a powered ankle-foot orthosis: the effects of actuation timing and stiffness level on healthy users – Full Text
In the last decades, several powered ankle-foot orthoses have been developed to assist the ankle joint of their users during walking. Recent studies have shown that the effects of the assistance provided by powered ankle-foot orthoses depend on the assistive profile. In compliant actuators, the stiffness level influences the actuator’s performance. However, the effects of this parameter on the users has not been yet evaluated. The goal of this study is to assess the effects of the assistance provided by a variable stiffness ankle actuator on healthy young users. More specifically, the effect of different onset times of the push-off torque and different actuator’s stiffness levels has been investigated.
Eight healthy subjects walked with a unilateral powered ankle-foot orthosis in several assisted walking trials. The powered orthosis was actuated in the sagittal plane by a variable stiffness actuator. During the assisted walking trials, three different onset times of the push-off assistance and three different actuator’s stiffness levels were used. The metabolic cost of walking, lower limb muscles activation, joint kinematics, and gait parameters measured during different assisted walking trials were compared to the ones measured during normal walking and walking with the powered orthosis not providing assistance.
This study found trends for more compliant settings of the ankle actuator resulting in bigger reductions of the metabolic cost of walking and soleus muscle activation in the stance phase during assisted walking as compared to the unassisted walking trial. In addition to this, the study found that, among the tested onset times, the earlier ones showed a trend for bigger reductions of the activation of the soleus muscle during stance, while the later ones led to a bigger reduction in the metabolic cost of walking in the assisted walking trials as compared to the unassisted condition.
This study presents a first attempt to show that, together with the assistive torque profile, also the stiffness level of a compliant ankle actuator can influence the assistive performance of a powered ankle-foot orthosis.
Powered ankle-foot orthoses (PAFOs) are robotic devices meant to assist the ankle joint of their users. Recently, several PAFOs have been developed and tested to investigate their potential in reducing the biological effort of healthy users during assisted walking as compared to unassisted or normal walking [1–5], but also to evaluate their performance when used as assistive or rehabilitation devices with weakened users such as the elderly [6, 7] and impaired subjects [8–10]. In these studies, PAFOs where shown to be able to reduce the metabolic cost of walking of healthy users as compared to the unassisted configuration [1, 5, 11], and in some cases also as compared to walking without the device [3, 4]. Furthermore, studies with impaired subjects showed the advantages of using a PAFO to improve the impaired ankle kinematics, to increase the walking speed of the assisted subject, and to improve the gait symmetry [8, 9, 12, 13]. Despite the promising results obtained by these studies, when comparing the performance of different PAFOs in achieving similar goals, differences exist in the outcomes of these experiments. As reported in , some studies have assessed the time needed by the users to adapt to the assistance provided by PAFOs. Although, several of these studies have shown that, over different identical sessions, the subjects reached a steady state increasingly faster [5, 11, 14–17], the resulting adaptation times differ between studies. In addition to this, different studies found divergent outcomes regarding the capabilities of PAFOs in reducing the metabolic cost and muscle activation of healthy users during powered walking [11, 14, 18–20]. The divergences come from the influence that some parameters of the assistive profile provided by the PAFO have on the user [1, 3, 13, 21, 22]. Recently, several research groups have evaluated the effects of two of these assistive parameters, which are the push-off onset time [1, 3, 21, 23] and the plantarflexion assistance magnitude [1, 22, 24, 25]. Specifically, these studies assessed the effect that different values of these parameters have on the biological effort of healthy users during walking. The results of these studies were analyzed and compared in . This work underlined that the optimal onset timing to minimize the metabolic cost of walking is not consistent between studies [1, 3, 21]. However, similar trends were found in different studies for which the optimal onset timing for the reduction of the soleus activation was earlier than the optimal onset timing for the reduction of the metabolic cost of walking [1, 21]. Different studies found that the reduction of the soleus activation is obtained with a bigger positive assistance magnitude, while a medium level of assistance magnitude is more beneficial to reduce the metabolic cost of walking [1, 22]. However, these findings are not compatible with the results obtained in [5, 20, 26]. Some studies tried to define some formulae predicting the performance of the assistance provided by the PAFOs on their users based on the assistive parameters [1, 4]. However, as highlighted in , the determination of this formula is not straightforward due to the mutual influence of different parameters and to the fact that the results can be influenced by the different actuation setups and different protocols used in different studies.
In the field of wearable robots, there is a shift towards the use of compliant actuators as actuation principles. Among them, variable stiffness actuators (VSAs) have been shown to be able to minimize large forces due to shocks, to be energy-efficient by storing and releasing energy, and to be robust to external perturbations or unpredictable model errors [27–29]. Despite the well-recognized benefits of VSAs, their employment in wearable robots is still limited due to their design complexity, the increased weight, and the challenging control strategies needed . Among the developed VSAs, the MACCEPA has been already implemented in wearable robots such as lower limbs exoskeletons [31–33] and powered knee [34–36] and ankle orthoses [37–39].
This study evaluates the effects of a MACCEPA-actuated unilateral PAFO, named MAPO (Maccepa Ankle Powered Orthosis) on the walking performance of healthy young users. More specifically, the goal of this study is to evaluate the specific effects of different assistive parameters on the biological effort (i.e., metabolic cost of walking and lower limbs muscle activation) and walking pattern (i.e., lower limbs kinematics and gait parameters) of healthy users. As previously introduced, one of the assistance parameters influencing the PAFO’s assistive performance on the user is the onset timing of the powered push-off. For this reason, the effects of this assistance parameter are investigated with subjects walking with the MAPO. The second parameter investigated in this study is the actuator’s stiffness level. The influence of this parameter on the actuator’s performance has been already shown in several test-bench experiments [37, 40]. In  it was shown that no single stiffness level of the ankle actuator used in the MAPO could be defined as optimal based on the actuator’s torque tracking performance, due to the dependence of the benefits of a specific actuator’s stiffness level on both the assistive torque reference and the user’s ankle kinematics. However, the effect of the actuator’s stiffness level on the users has not been yet studied. Thus, a goal of this study is to assess whether the actuator’s stiffness has an influence on the walking performance of healthy users. As previously mentioned, the results of previous studies with bilateral PAFOs [1, 21] showed that the push-off onset time has an influence on the biological effort of healthy users. For this reason, the onset timing of the assistance provided by the MAPO is expected to have an influence on the biological effort of the users. Nevertheless, an additional goal of this study is to evaluate whether similar trends to the ones obtained in [1, 21] can be seen when walking with a unilateral PAFO.
Eight healthy male subjects (age 29.8 ±2.6years, height 1.79 ±0.07m, weight 76.5 ±6.5kg, leg length 0.92 ±0.05m) volunteered to participate in the study. All subjects signed the informed consent (in accordance with the General Data Protection Regulation).
MAPO hardware and control strategy
The PAFO used during the experiments is called MAPO and it is shown in Fig. 1. The design and characterization of the MACCEPA-based ankle actuator implemented in the MAPO have been already presented in detail in [37, 38]. Briefly, the ankle VSA is used to actuate the MAPO in both directions of the sagittal plane (Additional file 1). The actuator’s stiffness level can be changed by modifying the pre-compression (P) of its spring. P is indicated as a percentage of the working length of the spring (spring constant 68.7kN/m, natural length 0.051m, maximal travel of work 0.019m ). A level of P equal to 0% indicates that the spring at the actuator’s equilibrium position is uncompressed, while P equal to 100% indicates that the spring is completely compressed at the actuator’s equilibrium position. Thus, the actuator’s behavior is more compliant for lower levels of the spring pre-compression (P). It should be noted that the actuator’s stiffness is not the output stiffness, because the actuator characteristics are not defined as a function of the actuator’s output angle (i.e. the angle between the shank and the foot link), as reported in the Additional file 1 and in [36, 38].
A new line of wearable robotics developed by The University of Texas Health Science Center at Houston (UTHealth) and The City University of New York, City College (CCNY) could keep seniors on their feet longer. A prototype developed by Hao Su, PhD, an assistant professor at CCNY, and tested by Gerard Francisco, MD, and Shuo-Hsiu (James) Chang, PT, PhD, of McGovern Medical School at UTHealth, fared well in a pilot study of people with walking difficulties. Now with the support of a $1.3 million grant from the National Institute on Disability, Independent Living, and Rehabilitation Research, the three researchers plan to evaluate the model on seniors who have difficulty with their gait or stride.
Conventional exoskeletons are typically heavy, bulky, expensive, and primarily suitable for individuals with little voluntary movement. In contrast, the hybrid soft exoskeleton developed by the team is 60% lighter than commercially available exoskeletons and less costly. It combines the advantages of rigid exoskeletons and textile-based exosuits with assistive control algorithms to monitor, augment, and compensate for the loss of gait function. “Our model is run by the user, not the robot. Wearers aren’t forced to walk in a predefined path,” said Francisco, the chair of physical medicine and rehabilitation at McGovern Medical School and the chief medical officer at TIRR Memorial Hermann, Houston.
The team’s long-term vision is to make assistive robots accessible to everyone who needs them, said Chang, assistant professor of physical medicine and rehabilitation at McGovern Medical School and the administrative director of the NeuroRecovery Research Center at TIRR Memorial Hermann. “There is a pressing need for wearable robots that can improve the quality of life for broader populations in community settings,” he said.
[Abstract] Methodology for the Design of Rehabilitation Robots: Application in an Exoskeleton for Upper Limb Rehabilitation – Full Text PDF
This article presents a methodology for the design of rehabilitation devices that considers factors involved in a clinical environment. This methodology integrates different disciplines that work together. The methodology is composed by 3 phases and 13 stages with specific tasks, the first phase includes the clinical context considering the requirements of the patient and therapist during the rehabilitation, the second phase is focused in engineering based on the philosophy of digital twin, and in the third phase is evaluated the device. This article explains the characteristics of the methodology and how it was applied in the design of an exoskeleton for passive rehabilitation of the upper limb.
[ARTICLE] The ReWalk ReStore™ soft robotic exosuit: a multi-site clinical trial of the safety, reliability, and feasibility of exosuit-augmented post-stroke gait rehabilitation – Full Text
Atypical walking in the months and years after stroke constrain community reintegration and reduce mobility, health, and quality of life. The ReWalk ReStore™ is a soft robotic exosuit designed to assist the propulsion and ground clearance subtasks of post-stroke walking by actively assisting paretic ankle plantarflexion and dorsiflexion. Previous proof-of-concept evaluations of the technology demonstrated improved gait mechanics and energetics and faster and farther walking in users with post-stroke hemiparesis. We sought to determine the safety, reliability, and feasibility of using the ReStore™ during post-stroke rehabilitation.
A multi-site clinical trial (NCT03499210) was conducted in preparation for an application to the United States Food and Drug Administration (FDA). The study included 44 users with post-stroke hemiparesis who completed up to 5 days of training with the ReStore™ on the treadmill and over ground. In addition to primary and secondary endpoints of safety and device reliability across all training activities, an exploratory evaluation of the effect of multiple exposures to using the device on users’ maximum walking speeds with and without the device was conducted prior to and following the five training visits.
All 44 study participants completed safety and reliability evaluations. Thirty-six study participants completed all five training days. No device-related falls or serious adverse events were reported. A low rate of device malfunctions was reported by clinician-operators. Regardless of their reliance on ancillary assistive devices, after only 5 days of walking practice with the device, study participants increased both their device-assisted (Δ: 0.10 ± 0.03 m/s) and unassisted (Δ: 0.07 ± 0.03 m/s) maximum walking speeds (P’s < 0.05).
When used under the direction of a licensed physical therapist, the ReStore™ soft exosuit is safe and reliable for use during post-stroke gait rehabilitation to provide targeted assistance of both paretic ankle plantarflexion and dorsiflexion during treadmill and overground walking.
Bipedal locomotion is characterized by alternating periods of single and double limb support, with ground clearance by the swing limb and propulsion by the trailing stance limb serving as crucial walking subtasks [1, 2]. Healthy individuals are able to generate an ankle dorsiflexion moment during each limb’s swing phase to lift the foot and facilitate ground clearance. They are also able to generate an ankle plantarflexion moment during each limb’s late stance phase to produce the propulsive force required to advance the limb and body . In contrast, post-stroke hemiparesis results in impaired paretic dorsiflexion and plantarflexion that, in turn, hinders ground clearance and propulsion [4,5,6,7,8] and, ultimately, necessitates compensatory walking strategies [9, 10] that make walking more effortful and unstable [11,12,13,14].
The ReWalk ReStore™ is a soft robotic exosuit designed to augment the paretic ankle’s ability to produce both dorsiflexor and plantarflexor moments during walking. In early proof-of-concept studies conducted with a research version of the device [15, 16], exosuits were shown to facilitate immediate increases in swing phase paretic ankle dorsiflexion by an average 5 degrees , the propulsion force generated by the paretic limb by an average 10% , and the positive center of mass (COM) power generated by the paretic limb during late stance phase by an average 22% . Together, these improvements in paretic limb function resulted in reduced propulsion asymmetry by 20%  and the asymmetry in positive COM power generated during late stance phase by 39% . Also observed were immediate reductions in hip hiking and circumduction compensations of over 20% , reductions in the energy cost of walking by an average 10% [17, 18], faster overground walking speeds by a median 0.14 m/s, and farther walking distances during the 6-min walk test by a median 32m .
Building on this foundational biomechanical, physiological, and clinical research, the objective of this multi-site clinical trial was to evaluate safety, feasibility, and reliability of using exosuits during post-stroke rehabilitation in preparation for a commercial clinical application to the United States Food and Drug Administration (FDA). In contrast to previous laboratory-based research that studied the immediate effects of exosuit prototypes on clinical, biomechanical, and physiological outcomes, this translational research sought to determine the safety of clinicians and patients with post-stroke hemiparesis using the commercially-adapted ReStore™ in clinical settings, the feasibility of clinician operators applying the ReStore™ during both treadmill and over ground gait training activities, and the reliability of the technology across multiple training visits. In addition to outcomes of safety, feasibility, and device reliability, an exploratory evaluation of the impact that multiple training visits with the device have on users’ maximum walking speeds, both with and without the device, was also included.
The ReStore™ is indicated for use by individuals with post-stroke hemiparesis undergoing stroke rehabilitation under the supervision of a licensed physical therapist. To assess the safety, device reliability, and clinical feasibility of using the ReStore™ during post-stroke gait rehabilitation, a multi-site trial was conducted. The trial included five clinical sites and 44 users with post-stroke hemiparesis. The study was approved by the Institutional Review Boards of Boston University, Spaulding Rehabilitation Hospital, The Shirley Ryan AbilityLab, TIRR Memorial Hermann Hospital, Kessler Rehabilitation Hospital, and Moss Rehabilitation Hospital. Written informed consent was secured for all participants.
Study inclusion and exclusion criteria
Study participant eligibility requirements consisted of: (i) one-sided ischemic or hemorrhagic stroke, (ii) > 2 weeks post-stroke, (iii) age > 18 years, (iv) height between 4′8″ and 6′7″, (v) weight < 264lbs, (vi) medical clearance, (vii) ability to ambulate at least 5 ft without an AFO and with no more than minimal contact assistance, (viii) ability to follow a 3-step command, (ix) ability to fit suit components, (x) no greater than 5 degrees of ankle plantar flexion contracture, and (xi) Modified Ashworth Scale for tone at 3 or less for ankle dorsiflexor and plantarflexor muscles. Exclusion criteria included: (i) severe aphasia limiting ability to express needs or discomfort verbally or non-verbally, (ii) serious co-morbidities that interfere with ability to participate, (iii) significant Peripheral Artery Disease, (iv) colostomy bag, (v) current pregnancy, (vi) uncontrolled hypertension, (vii) participation in any other clinical trial, (viii) open wounds or broken skin at device locations requiring medical management, (ix) urethane allergies, (x) and current DVT.
After screening and enrollment, study participants completed up to two walking evaluations and five device exposure visits. Each exposure visit consisted of up to 20 min of overground walking practice and 20 min of treadmill walking practice while receiving assistance from the device. The visit schedule consisted of a minimum of two visits per week, with the expectation of no more than 4 weeks between the pretraining and posttraining evaluations. Actual activities and durations were dependent on each study participant’s abilities as determined by the treating physical therapist as per their usual practices. The target level for plantarflexion assistance during all active walking with the ReStore™ was 25% of the user’s bodyweight [17, 19]. The target level for dorsiflexion assistance was the minimum needed for adequate ground clearance and heel strike, as determined visually by the physical therapist.
The exosuit consists of motors worn at the waist that generate mechanical forces that are transmitted by cables to attachment points located proximally on a functional textile worn around the calf and distally on a shoe insole (Fig. 1). The overall weight of the exosuit is approximately 5kgs, with the vast majority of the weight located proximally in the actuation pack worn at the waist. Each functional textile contains a detachable liner that can be washed. For users who require medio-lateral ankle support in addition to ankle plantarflexion and dorsiflexion assistance, an optional textile component that prevents ankle inversion without restricting dorsiflexion and plantarflexion can also be used. Inertial sensors that attach to a patient’s shoes measure gait events and automate the independent timing of the active ankle plantarflexion and dorsiflexion assistance provided by the ReStore™ as previously described . Load cell sensors located at the end of each cable are used to monitor the interaction between user and exosuit and ensure that the target level of assistance is achieved [16, 17]. A hand-held device with a graphical interface allows clinicians to monitor patients’ performance and select and progress, in real-time, the assistance parameters (Fig. 2).