Heart rate and oxygen demand of powered exoskeleton-assisted walking in persons with paraplegia

The Pathophysiology, Identification and Management of Fracture Risk, Sublesional Osteoporosis and Fracture among Adults with Spinal Cord Injury

BACKGROUND

The prevention of lower extremity fractures and fracture-related morbidity and mortality is a critical component of health services for adults living with chronic spinal cord injury (SCI).

METHODS

Established best practices and guideline recommendations are articulated in recent international consensus documents from the International Society of Clinical Densitometry, the Paralyzed Veterans of America Consortium for Spinal Cord Medicine and the Orthopedic Trauma Association.

RESULTS

This review is a synthesis of the aforementioned consensus documents, which highlight the pathophysiology of lower extremity bone mineral density (BMD) decline after acute SCI. The role and actions treating clinicians should take to screen, diagnose and initiate the appropriate treatment of established low bone mass/osteoporosis of the hip, distal femur or proximal tibia regions associated with moderate or high fracture risk or diagnose and manage a lower extremity fracture among adults with chronic SCI are articulated. Guidance regarding the prescription of dietary calcium, vitamin D supplements, rehabilitation interventions (passive standing, functional electrical stimulation (FES) or neuromuscular electrical stimulation (NMES)) to modify bone mass and/or anti-resorptive drug therapy (Alendronate, Denosumab, or Zoledronic Acid) is provided. In the event of lower extremity fracture, the need for timely orthopedic consultation for fracture diagnosis and interprofessional care following definitive fracture management to prevent health complications (venous thromboembolism, pressure injury, and autonomic dysreflexia) and rehabilitation interventions to return the individual to his/her pre-fracture functional abilities is emphasized.

CONCLUSIONS

Interprofessional care teams should use recent consensus publications to drive sustained practice change to mitigate fracture incidence and fracture-related morbidity and mortality among adults with chronic SCI.

Satisfaction analysis of overground gait exoskeletons in people with neurological pathology. a systematic review

BACKGROUND

People diagnosed with neurological pathology may experience gait disorders that affect their quality of life. In recent years, research has been carried out on a variety of exoskeletons in this population. However, the satisfaction perceived by the users of these devices is not known. Therefore, the objective of the present study is to evaluate the satisfaction perceived by users with neurological pathology (patients and professionals) after the use of overground exoskeletons.

METHODS

A systematic search of five electronic databases was conducted. In order to be included in this review for further analysis, the studies had to meet the following criteria: [1] the study population was people diagnosed with neurological pathology; [2] the exoskeletons had to be overground and attachable to the lower limbs; and [3]: the studies were to include measures assessing either patient or therapist satisfaction with the exoskeletons.

RESULTS

Twenty-three articles were selected, of which nineteen were considered clinical trials. Participants diagnosed with stroke (n = 165), spinal cord injury (SCI) (n = 102) and multiple sclerosis (MS) (n = 68). Fourteen different overground exoskeleton models were analysed. Fourteen different methods of assessing patient satisfaction with the devices were found, and three ways to evaluate it in therapists.

CONCLUSION

Users' satisfaction with gait overground exoskeletons in stroke, SCI and MS seems to show positive results in safety, efficacy and comfort of the devices. However, the worst rated aspects and therefore those that should be optimized from the users' point of view are ease of adjustment, size and weight, and ease of use.

Comparison of the dynamics of exoskeletal-assisted and unassisted locomotion in an FDA-approved lower extremity device: Controlled experiments and development of a subject-specific virtual simulator

Robotic exoskeletons have considerable, but largely untapped, potential to restore mobility in individuals with neurological disorders, and other conditions that result in partial or complete immobilization. The growing demand for these devices necessitates the development of technology to characterize the human-robot system during exoskeletal-assisted locomotion (EAL) and accelerate robot design refinements. The goal of this study was to combine controlled experiments with computational modeling to build a virtual simulator of EAL. The first objective was to acquire a minimum empirical dataset comprising human-robot kinematics, ground reaction forces, and electromyography during exoskeletal-assisted and unassisted locomotion from an able-bodied participant. The second objective was to quantify the dynamics of the human-robot system using a subject-specific virtual simulator reproducing EAL compared to the dynamics of normal gait. We trained an able-bodied participant to ambulate independently in a Food and Drug Administration-approved exoskeleton, the ReWalk P6.0 (ReWalk Robotics, Yoknaem, Israel). We analyzed the motion of the participant during exoskeletal-assisted and unassisted walking, sit-to-stand, and stand-to-sit maneuvers, with simultaneous measurements of (i) three-dimensional marker trajectories, (ii) ground reaction forces, (iii) electromyography, and (iv) exoskeleton encoder data. We created a virtual simulator in OpenSim, comprising a whole-body musculoskeletal model and a full-scale exoskeleton model, to determine the joint kinematics and moments during exoskeletal-assisted and unassisted maneuvers. Mean peak knee flexion angles of the human subject during exoskeletal-assisted walking were 50.1° ± 0.6° (left) and 52.6° ± 0.7° (right), compared to 68.6° ± 0.3° (left) and 70.7° ± 1.1° (right) during unassisted walking. Mean peak knee extension moments during exoskeletal-assisted walking were 0.10 ± 0.10 Nm/kg (left) and 0.22 ± 0.11 Nm/kg (right), compared to 0.64 ± 0.07 Nm/kg (left) and 0.73 ± 0.10 Nm/kg (right) during unassisted walking. This work provides a foundation for parametric studies to characterize the effects of human and robot design variables, and predictive modeling to optimize human-robot interaction during EAL.

Gait robot-assisted rehabilitation in persons with spinal cord injury: A scoping review

BACKGROUND

Many robots are available for gait rehabilitation (BWSTRT and ORET) and their application in persons with SCI allowed an improvement of walking function.

OBJECTIVE

The aim of the study is to compare the effects of different robotic exoskeletons gait training in persons with different SCI level and severity.

METHODS

Sixty-two studies were included in this systematic review; the study quality was assessed according to GRADE and PEDro's scale.

RESULTS

Quality assessment of included studies (n = 62) demonstrated a prevalence of evidence level 2; the quality of the studies was higher for BWSTRT (excellent and good) than for ORET (fair and good). Almost all persons recruited for BWSTRT had an incomplete SCI; both complete and incomplete SCI were recruited for ORET. The SCI lesion level in the persons recruited for BWSTRT are from cervical to sacral; mainly from thoracic to sacral for ORET; a high representation of AIS D lesion resulted both for BWSTRT (30%) and for ORET (45%). The walking performance, tested with 10MWT, 6MWT, TUG and WISCI, improved after exoskeleton training in persons with incomplete SCI lesions, when at least 20 sessions were applied. Persons with complete SCI lesions improved the dexterity in walking with exoskeleton, but did not recover independent walking function; symptoms such as spasticity, pain and cardiovascular endurance improved.

CONCLUSION

Different exoskeletons are available for walking rehabilitation in persons with SCI. The choice about the kind of robotic gait training should be addressed on the basis of the lesion severity and the possible comorbidities.

Patients' and therapists' experience and perception of exoskeleton-based physiotherapy during subacute stroke rehabilitation: a qualitative analysis

PURPOSE

To explore the experience and acceptability of an exoskeleton-based physiotherapy program for non-ambulatory patients during subacute stroke rehabilitation from the perspective of patients and therapists.

MATERIALS AND METHODS

This was a qualitative descriptive study using semi-structured interviews and thematic analysis. Fourteen patients with stroke who participated in the experimental arm of a randomized controlled trial investigating the efficacy of exoskeleton-based physiotherapy were recruited. Six physiotherapists who provided the intervention were also recruited.

RESULTS

Three themes were identified relating to the experience and acceptability of an exoskeleton-based physiotherapy program: (1) A matter of getting into the swing of things depicted the initial and ongoing learning process of using an exoskeleton; (2) More of a positive experience than anything else described the participants' mostly favorable attitude toward exoskeleton-based gait training; and (3) The best step forward captured participant-identified recommendations and considerations for the future integration of exoskeleton training into stroke rehabilitation.

CONCLUSIONS

Patients with stroke were even more optimistic than therapists toward the experience and benefits of exoskeleton-based gait training during subacute stroke rehabilitation. Future clinical practice should consider the balance between actual and perceived benefits, as well as the potential barriers to integrating an exoskeleton into stroke rehabilitation.IMPLICATIONS FOR REHABILITATIONPowered robotic exoskeletons can be used to provide higher duration and more repetitious walking practice for non-ambulatory patients with stroke.Patients with stroke view exoskeleton-based physiotherapy highly favorably, attributing greater opportunity and benefit to using the device during subacute rehabilitation.Physiotherapists should consider learning challenges, patient characteristics, and implementation barriers when integrating exoskeleton-based training within a treatment program.

Systemic inflammation after spinal cord injury: A review of biological evidence, related health risks, and potential therapies

Individuals with chronic traumatic spinal cord injury (SCI) develop progressive multi-system health problems that result in clinical illness and disability. Systemic inflammation is associated with many of the common medical complications and acquired diseases that accompany chronic SCI, suggesting that it contributes to a number of comorbid pathological conditions. However, many of the mechanisms that promote persistent systemic inflammation and its consequences remain ill-defined. This review describes the significant biological factors that contribute to systemic inflammation, major organ systems affected, health risks, and the potential treatment strategies. We aim to highlight the need for a better understanding of inflammatory processes, and to establish appropriate strategies to address inflammation in SCI.

Lower Limb Exoskeleton Sensors: State-of-the-Art

Due to the ever-increasing proportion of older people in the total population and the growing awareness of the importance of protecting workers against physical overload during long-time hard work, the idea of supporting exoskeletons progressed from high-tech fiction to almost commercialized products within the last six decades. Sensors, as part of the perception layer, play a crucial role in enhancing the functionality of exoskeletons by providing as accurate real-time data as possible to generate reliable input data for the control layer. The result of the processed sensor data is the information about current limb position, movement intension, and needed support. With the help of this review article, we want to clarify which criteria for sensors used in exoskeletons are important and how standard sensor types, such as kinematic and kinetic sensors, are used in lower limb exoskeletons. We also want to outline the possibilities and limitations of special medical signal sensors detecting, e.g., brain or muscle signals to improve data perception at the human-machine interface. A topic-based literature and product research was done to gain the best possible overview of the newest developments, research results, and products in the field. The paper provides an extensive overview of sensor criteria that need to be considered for the use of sensors in exoskeletons, as well as a collection of sensors and their placement used in current exoskeleton products. Additionally, the article points out several types of sensors detecting physiological or environmental signals that might be beneficial for future exoskeleton developments.

Comparing walking with knee-ankle-foot orthoses and a knee-powered exoskeleton after spinal cord injury: a randomized, crossover clinical trial

Recovering the ability to stand and walk independently can have numerous health benefits for people with spinal cord injury (SCI). Wearable exoskeletons are being considered as a promising alternative to conventional knee-ankle-foot orthoses (KAFOs) for gait training and assisting functional mobility. However, comparisons between these two types of devices in terms of gait biomechanics and energetics have been limited. Through a randomized, crossover clinical trial, this study compared the use of a knee-powered lower limb exoskeleton (the ABLE Exoskeleton) against passive orthoses, which are the current standard of care for verticalization and gait ambulation outside the clinical setting in people with SCI. Ten patients with SCI completed a 10-session gait training program with each device followed by user satisfaction questionnaires. Walking with the ABLE Exoskeleton improved gait kinematics compared to the KAFOs, providing a more physiological gait pattern with less compensatory movements (38% reduction of circumduction, 25% increase of step length, 29% improvement in weight shifting). However, participants did not exhibit significantly better results in walking performance for the standard clinical tests (Timed Up and Go, 10-m Walk Test, and 6-min Walk Test), nor significant reductions in energy consumption. These results suggest that providing powered assistance only on the knee joints is not enough to significantly reduce the energy consumption required by people with SCI to walk compared to passive orthoses. Active assistance on the hip or ankle joints seems necessary to achieve this outcome.

Generation of a Reference Dataset to Permit the Calculation of T-scores at the Distal Femur and Proximal Tibia in Persons with Spinal Cord Injury

Persons with traumatic spinal cord injury (SCI) have severe bone loss below the level of lesion with the distal femur (DF) and proximal tibia (PT) being the skeletal regions having the highest risk of fracture. While a reference areal bone mineral density (aBMD) database is available at the total hip (TH) using the combined National Health and Nutrition Examination Survey (NHANES) III study and General Electric (GE) combined (GE/NHANES) to calculate T-score (T-score_GE/NHANES), no such reference database exists for aBMD of the DF, and PT. The primary objectives of this study were (1) to create a reference dataset of young-healthy able-bodied (YHAB) persons to calculate T-score (T-score_YHAB) values at the DF and PT, (2) to explore the impact of time since injury (TSI) on relative bone loss in the DF and PT regions using the two computation models to determine T-score values, and (3) to determine agreement between T-score values for a cohort of persons with SCI using the (T-score_YHAB) and (T-score_GE/NHANES) reference datasets. A cross-sectional prospective data collection study. A Department of Veterans Affairs Medical Center and a Private Rehabilitation Hospital. A normative reference aBMD database at the DF and PT was collected in 32 male and 32 female Caucasian YHAB participants (n=64) and then applied to calculate T-score values at the DF and PT in 105 SCI participants from a historical cohort. The SCI participants were then grouped based on TSI epochs (E-I: TSI < 1y, E-II: TSI 1-5y, E-III: TSI 6-10y, E-IV: TSI 11-20y, E-V: TSI > 20y). N/A. The knee and hip aBMD values were obtained by dual energy X-ray absorptiometry (GE Lunar iDXA) using standard clinical software for proximal femur orthopedic knee software applications. There were no significant differences in mean aBMD values across the four YHAB age subgroups (21-25, 26-30, 31-35, and 36-40 yr of age) at the TH, DF, and PT; mean aBMD values were higher in men compared to the women at all skeletal regions of interest. Using the mean YHAB aBMD values to calculate T-score values at each TSI epoch for persons with SCI, T-score values decreased as a function of TSI, and they continued to decline for 11-20 yr. Moderate kappa agreement was noted between the YHAB and the GE/NHANES reference datasets for the T-score cutoff criteria accepted to diagnose osteoporosis (i.e., SD <-2.5). A homogeneous reference dataset of YHAB aBMD values at the DF and PT was applied to calculate T-score values in persons with chronic SCI. There was a moderate level of agreement at the TH between the YHAB and GE/NHANES reference datasets when applying the conventional T-score cutoff value for the diagnosis of osteoporosis.

Feasibility of Overground Gait Training Using a Joint-Torque-Assisting Wearable Exoskeletal Robot in Children with Static Brain Injury

Pediatric gait disorders are often chronic and accompanied by various complications, which challenge rehabilitation efforts. Here, we retrospectively analyzed the feasibility of overground robot-assisted gait training (RAGT) using a joint-torque-assisting wearable exoskeletal robot. In this study, 17 children with spastic cerebral palsy, cerebellar ataxia, and chronic traumatic brain injury received RAGT sessions. The Gross Motor Function Measure (GMFM), 6-min walk test (6 MWT), and 10-m walk test (10 MWT) were performed before and after intervention. The oxygen rate difference between resting and training was performed to evaluate the intensity of training in randomly selected sessions, while the Quebec User Evaluation of Satisfaction with assistive Technology 2.0 assessment was performed to evaluate its acceptability. A total of four of five items in the GMFM, gait speed on the 10 MWT, and total distance on the 6 MWT showed statistically significant improvement (p < 0.05). The oxygen rate was significantly higher during the training versus resting state. Altogether, six out of eight domains showed satisfaction scores more than four out of five points. In conclusion, overground training using a joint-torque-assisting wearable exoskeletal robot showed improvement in gross motor and gait functions after the intervention, induced intensive gait training, and achieved high satisfaction scores in children with static brain injury.

The Cardiorespiratory Demands of Treadmill Walking with and without the Use of Ekso GT™ within Able-Bodied Participants: A Feasibility Study

Individuals with neurological impairments tend to lead a predominantly sedentary lifestyle due to impaired gait function and mobility. This may be detrimental to health by negatively impacting cardiorespiratory fitness and muscular strength, and increasing the risk of developing secondary health problems. Powered exoskeletons are assistive devices that may aid neurologically impaired individuals in achieving the World Health Organisation's (WHO) physical activity (PA) guidelines for health. Increased PA should elicit a sufficient cardiorespiratory stimulus to provide health benefits to exoskeleton users. This study examined the cardiorespiratory demands of treadmill walking with and without the Ekso GT™ among able-bodied participants. The Ekso GT™ is a powered exoskeleton that enables individuals with neurological impairments to walk by supporting full body mass with motors attached at the hip and knee joints to generate steps. This feasibility study consisted of one group of healthy able-bodied individuals (n = 8). Participants completed two 12 min treadmill walking assessments, one with and one without the Ekso GT™ at the same fixed speed. Throughout each walking bout, various cardiorespiratory parameters, namely, volume of oxygen per kilogram (kg) of body mass (V˙O2·kg-1), volume of carbon dioxide per kg of body mass (V˙CO2·kg-1), respiratory exchange ratio (RER), ventilation (V˙E), heart rate (HR), and rate of perceived exertion (RPE), were recorded. Treadmill walking with Ekso GT™ elevated all recorded measurements to a significantly greater level (p ≤ 0.05) (except RER at 1 km·h-1; p = 0.230) than treadmill walking without the Ekso GT™ did at the same fixed speed. An increased cardiorespiratory response was recorded during treadmill walking with the exoskeleton. Exoskeleton walking may, therefore, be an effective method to increase PA levels and provide sufficient stimulus in accordance with the PA guidelines to promote cardiorespiratory fitness and subsequently enhance overall health.

Overground robotic training effects on walking and secondary health conditions in individuals with spinal cord injury: systematic review

Overground powered lower limb exoskeletons (EXOs) have proven to be valid devices in gait rehabilitation in individuals with spinal cord injury (SCI). Although several articles have reported the effects of EXOs in these individuals, the few reviews available focused on specific domains, mainly walking. The aim of this systematic review is to provide a general overview of the effects of commercial EXOs (i.e. not EXOs used in military and industry applications) for medical purposes in individuals with SCI. This systematic review was conducted following the PRISMA guidelines and it referred to MED-LINE, EMBASE, SCOPUS, Web of Science and Cochrane library databases. The studies included were Randomized Clinical Trials (RCTs) and non-RCT based on EXOs intervention on individuals with SCI. Out of 1296 studies screened, 41 met inclusion criteria. Among all the EXO studies, the Ekso device was the most discussed, followed by ReWalk, Indego, HAL and Rex devices. Since 14 different domains were considered, the outcome measures were heterogeneous. The most investigated domain was walking, followed by cardiorespiratory/metabolic responses, spasticity, balance, quality of life, human–robot interaction, robot data, bowel functionality, strength, daily living activity, neurophysiology, sensory function, bladder functionality and body composition/bone density domains. There were no reports of negative effects due to EXOs trainings and most of the significant positive effects were noted in the walking domain for Ekso, ReWalk, HAL and Indego devices. Ekso studies reported significant effects due to training in almost all domains, while this was not the case with the Rex device. Not a single study carried out on sensory functions or bladder functionality reached significance for any EXO. It is not possible to draw general conclusions about the effects of EXOs usage due to the lack of high-quality studies as addressed by the Downs and Black tool, the heterogeneity of the outcome measures, of the protocols and of the SCI epidemiological/neurological features. However, the strengths and weaknesses of EXOs are starting to be defined, even considering the different types of adverse events that EXO training brought about. EXO training showed to bring significant improvements over time, but whether its effectiveness is greater or less than conventional therapy or other treatments is still mostly unknown. High-quality RCTs are necessary to better define the pros and cons of the EXOs available today. Studies of this kind could help clinicians to better choose the appropriate training for individuals with SCI.

Knowledge Gaps in Biophysical Changes After Powered Robotic Exoskeleton Walking by Individuals With Spinal Cord Injury—A Scoping Review

In addition to helping individuals with spinal cord injury (SCI) regain the ability to ambulate, the rapidly evolving capabilities of robotic exoskeletons provide an array of secondary biophysical benefits which can reduce the complications resulting from prolonged immobilization. The proposed benefits of increased life-long over-ground walking capacity include improved upper body muscular fitness, improved circulatory response, improved bowel movement regularity, and reduced pain and spasticity. Beyond the positive changes related to physical and biological function, exoskeletons have been suggested to improve SCI individuals' quality of life (QOL) by allowing increased participation in day-to-day activities. Most of the currently available studies that have reported on the impact of exoskeletons on the QOL and prevention of secondary health complications on individuals with SCI, are of small scale and are heterogeneous in nature. Moreover, few meta-analyses and reviews have attempted to consolidate the dispersed data to reach more definitive conclusions of the effects of exoskeleton use. This scoping review seeks to provide an overview on the known effects of overground exoskeleton use, on the prevention of secondary health complications, changes to the QOL, and their effect on the independence of SCI individuals in the community settings. Moreover, the intent of the review is to identify gaps in the literature currently available, and to make recommendations on focus study areas and methods for future investigations.

Exoskeletons for Mobility after Spinal Cord Injury: A Personalized Embodied Approach

Endowed with inherent flexibility, wearable robotic technologies are powerful devices that are known to extend bodily functionality to assist people with spinal cord injuries (SCIs). However, rather than considering the specific psychological and other physiological needs of their users, these devices are specifically designed to compensate for motor impairment. This could partially explain why they still cannot be adopted as an everyday solution, as only a small number of patients use lower-limb exoskeletons. It remains uncertain how these devices can be appropriately embedded in mental representations of the body. From this perspective, we aimed to highlight the homeostatic role of autonomic and interoceptive signals and their possible integration in a personalized experience of exoskeleton overground walking. To ensure personalized user-centered robotic technologies, optimal robotic devices should be designed and adjusted according to the patient's condition. We discuss how embodied approaches could emerge as a means of overcoming the hesitancy toward wearable robots.

Wearable Power-Assist Locomotor for Gait Reconstruction in Patients With Spinal Cord Injury: A Retrospective Study

Wearable robotic exoskeletons (WREs) have been developed from orthoses as assistive devices for gait reconstruction in patients with spinal cord injury. They can solve some problems encountered with orthoses, such as difficulty in independent walking and standing up and high energy consumption during walking. The Wearable Power-Assist Locomotor (WPAL), a WRE, was developed based on a knee–ankle–foot orthosis with a single medial hip joint. The WPAL has been updated seven times during the period from the beginning of its development, in 2005, to 2020. The latest version, launched as a commercialized model in 2016, is available for medical facilities. In this retrospective study, which included updated results from previous reports, all data were extracted from development research records from July 2007 to December 2020. The records were as follows: patient characteristics [the number of participants, injury level, and the American Spinal Injury Association Impairment Scale (AIS) score], the total number of WPAL trials when aggregating the cases with all the versions or only the latest version of the WPAL, and maximum walking performance (functional ambulation category [FAC], distance, and time of continuous walking). Thirty-one patients participated in the development research. The levels of spinal cord injury were cervical (C5–C8), upper thoracic (T3–T6), lower thoracic (T7–T12), and lumbar (L1) in 10, 5, 15, and 1 of the patients, respectively. The numbers of patients with AIS scores of A, B, C, and D were 20, 7, 4, and 0, respectively. The total number of WPAL trials was 1,785, of which 1,009 were used the latest version of the WPAL. Twenty of the patients achieved an FAC score of 4 after an average of 9 (median 8, range 2–22) WPAL trials. The continuous walking distance and time improved with the WPAL were compared to the orthosis. We confirmed that the WPAL improves walking independence in people with a wide range of spinal cord injuries, such as cervical spinal cord injuries. Further refinement of the WPAL will enable its long-term use at home.

Effect of Reciprocating Gait Orthosis with Hip Actuation on Upper Extremity Loading during Ambulation in Patient with Spinal Cord Injury: A Single Case Study

Reciprocating gait orthosis (RGO) is a traditional passive orthosis that provides postural stability and allows for independent upright ambulation with the assistance of walking aids, such as crutches, canes, and walkers. Previous follow-up studies of patients with RGOs have indicated a high frequency of nonusage. One of the main reasons for avoiding the use of RGOs is the excessive upper extremity loading induced by walking aids. The purpose of this study was to investigate the effect of hip actuation on the upper extremity loading induced by crutches when ambulating with an RGO. One female individual with a chronic complete spinal cord injury classified as ASIA A participated in this study. We compared the upper extremity loading during ambulation when individualized hip assistive forces were applied on the RGO (POWERED condition) and when wearing the RGO without actuation (RGO condition). Upper extremity loading was assessed by measuring the forces acting on the crutches. Compared with the RGO condition, the average upper extremity loading per unit distance and per unit time were lower for the POWERED condition by 15.21% (RGO: 0.307 ± 0.056 and POWERED: 0.260 ± 0.034 %bw·m−1) and by 21.19% (RGO: 0.120 ± 0.020 and POWERED: 0.094 ± 0.011 %bw·s−1), respectively. We believe that a substantial reduction in upper extremity loading during ambulation provided by hip actuation holds promise to promote long-term RGO use and enable patients with paraplegia to perform frequent and intensive rehabilitation training. As this is a single case study, subsequent studies should aim to verify this effect through a higher number of patients and to different injury levels.

Exoskeleton Training and Trans-Spinal Stimulation for Physical Activity Enhancement After Spinal Cord Injury (EXTra-SCI): An Exploratory Study

After spinal cord injury (SCI) physical activity levels decrease drastically, leading to numerous secondary health complications. Exoskeleton-assisted walking (EAW) may be one way to improve physical activity for adults with SCI and potentially alleviate secondary health complications. The effects of EAW may be limited, however, since exoskeletons induce passive movement for users who cannot volitionally contribute to walking. Trans-spinal stimulation (TSS) has shown the potential to enable those with even the most severe SCI to actively contribute to movements during EAW. To explore the effects of EAW training on improving secondary health complications in persons with SCI, participants with chronic (n = 8) were enrolled in an EAW program 2-3 times per week for 12 weeks. Anthropometrics (seated and supine waist and abdominal circumferences (WC and AC), body composition assessment (dual exposure x-ray absorptiometry-derived body fat percent, lean mass and total mass for the total body, legs, and trunk), and peak oxygen consumption (VO2 during a 6-minute walk test [6MWT]) were assessed before and after 12 weeks of EAW training. A subset of participants (n = 3) completed EAW training with concurrent TSS, and neuromuscular activity of locomotor muscles was assessed during a 10-m walk test (10MWT) with and without TSS following 12 weeks of EAW training. Upon completion of 12 weeks of training, reductions from baseline (BL) were found in seated WC (-2.2%, P = 0.036), seated AC (-2.9%, P = 0.05), and supine AC (-3.9%, P = 0.017). Percent fat was also reduced from BL for the total body (-1.4%, P = 0.018), leg (-1.3%, P = 0.018), and trunk (-2%, P = 0.036) regions. No effects were found for peak VO2. The addition of TSS for three individuals yielded individualized responses but generally increased knee extensor activity during EAW. Two of three participants who received TSS were also able to initiate more steps without additional assistance from the exoskeleton during a 10MWT. In summary, 12 weeks of EAW training significantly attenuated markers of obesity relevant to cardiometabolic health in eight men with chronic SCI. Changes in VO2 and neuromuscular activity with vs. without TSS were highly individualized and yielded no overall group effects.

Adaptation Strategies for Personalized Gait Neuroprosthetics

Personalization of gait neuroprosthetics is paramount to ensure their efficacy for users, who experience severe limitations in mobility without an assistive device. Our goal is to develop assistive devices that collaborate with and are tailored to their users, while allowing them to use as much of their existing capabilities as possible. Currently, personalization of devices is challenging, and technological advances are required to achieve this goal. Therefore, this paper presents an overview of challenges and research directions regarding an interface with the peripheral nervous system, an interface with the central nervous system, and the requirements of interface computing architectures. The interface should be modular and adaptable, such that it can provide assistance where it is needed. Novel data processing technology should be developed to allow for real-time processing while accounting for signal variations in the human. Personalized biomechanical models and simulation techniques should be developed to predict assisted walking motions and interactions between the user and the device. Furthermore, the advantages of interfacing with both the brain and the spinal cord or the periphery should be further explored. Technological advances of interface computing architecture should focus on learning on the chip to achieve further personalization. Furthermore, energy consumption should be low to allow for longer use of the neuroprosthesis. In-memory processing combined with resistive random access memory is a promising technology for both. This paper discusses the aforementioned aspects to highlight new directions for future research in gait neuroprosthetics.

Estimating Center of Mass Kinematics During Perturbed Human Standing Using Accelerometers

Estimating center of mass (COM) through sensor measurements is done to maintain walking and standing stability with exoskeletons. The authors present a method for estimating COM kinematics through an artificial neural network, which was trained by minimizing the mean squared error between COM displacements measured by a gold-standard motion capture system and recorded acceleration signals from body-mounted accelerometers. A total of 5 able-bodied participants were destabilized during standing through: (1) unexpected perturbations caused by 4 linear actuators pulling on the waist and (2) volitionally moving weighted jars on a shelf. Each movement type was averaged across all participants. The algorithm's performance was quantified by the root mean square error and coefficient of determination (R2) calculated from both the entire trial and during each perturbation type. Throughout the trials and movement types, the average coefficient of determination was 0.83, with 89% of the movements with R2 > .70, while the average root mean square error ranged between 7.3% and 22.0%, corresponding to 0.5- and 0.94-cm error in both the coronal and sagittal planes. COM can be estimated in real time for balance control of exoskeletons for individuals with a spinal cord injury, and the procedure can be generalized for other gait studies.

Human biomechanics perspective on robotics for gait assistance: challenges and potential solutions

Technological advancements in robotic devices have the potential to transform human mobility through gait assistance. However, the integration of physical hardware and software control algorithms with users to assist with impaired gait poses several challenges, such as allowing the user to adopt a variety of gaits and the process for evaluating the efficacy and performance of these assistive devices. Here, I discuss some of the challenges in the development of assistive devices and the use of biomechanical concepts and tools for control and test validation. Several potential solutions are proposed through the case study of one project that aimed to provide gait assistance for individuals with a spinal cord injury. Further challenges and future directions are discussed, with emphasis that diverse perspectives and approaches in gait assistance will accelerate engineering solutions towards regaining mobility.

Evaluation of safety and performance of the self balancing walking system Atalante in patients with complete motor spinal cord injury

STUDY DESIGN

Prospective, open label, observational.

OBJECTIVES

To present results of the first clinical study on a newly developed robotic exoskeleton (Atalante®, Wandercraft, Paris, France) that enables individuals with spinal cord injury (SCI) to perform ambulatory functions without technical aids.

SETTING

Two sites specialized in SCI rehabilitation, France.

METHODS

Inclusion criteria were presence of chronic complete SCI (AIS A) ranging from T5 to T12. The study protocol included 12 one-hour training sessions during 3 weeks. Patients walked on floor with robotic assistance and wore a harness connected to a mobile suspension system (without weight-bearing) to prevent from falling. Main outcome was the ability to walk 10 meters unassisted, secondary outcomes were assessment of other ambulatory functions, bladder and bowel functions, pain and spasticity.

RESULTS

Twelve patients were enrolled, and 11 completed the protocol, mean age 33,9 years. Six patients had T6 levels of lesion or above. Seven patients passed the 10mWT at the 12th session unassisted (mean walking speed 0.13 m/s) while four required some human help. All patients succeeded at the other ambulatory tests (stand-up, sit-down, balance, turn). There were no significant change for bladder (Qualiveen) or bowel (NBD) functions, neuropathic pain (NPSI, NPRS), yet five patients reported a subjective improvement of their bowel function. Impact on spasticity was variable depending on the muscle examined (Ashworth). Ischial skin erosion was seen in one patient that needed local dressing.

CONCLUSION

The Atalante system is safe and enables to perform ambulatory functions in patients with complete SCI.

Cardiorespiratory Responses to 10 Weeks of Exoskeleton-Assisted Overground Walking Training in Chronic Nonambulatory Patients with Spinal Cord Injury

Exercise intensity of exoskeleton-assisted walking in patients with spinal cord injury (SCI) has been reported as moderate. However, the cardiorespiratory responses to long-term exoskeleton-assisted walking have not been sufficiently investigated. We investigated the cardiorespiratory responses to 10 weeks of exoskeleton-assisted walking training in patients with SCI. Chronic nonambulatory patients with SCI were recruited from an outpatient clinic. Walking training with an exoskeleton was conducted three times per week for 10 weeks. Oxygen consumption and heart rate (HR) were measured during a 6-min walking test at pre-, mid-, and post-training. Exercise intensity was determined according to the metabolic equivalent of tasks (METs) for SCI and HR relative to the HR reserve (%HRR). Walking efficiency was calculated as oxygen consumption divided by walking speed. The exercise intensity according to the METs (both peak and average) corresponded to moderate physical activity and did not change after training. The %HRR demonstrated a moderate (peak %HRR) and light (average %HRR) exercise intensity level, and the average %HRR significantly decreased at post-training compared with mid-training (31.6 ± 8.9% to 24.3 ± 7.3%, p = 0.013). Walking efficiency progressively improved after training. Walking with an exoskeleton for 10 weeks may affect the cardiorespiratory system in chronic patients with SCI.

Patterns of whole-body muscle activations following vertical perturbations during standing and walking

BACKGROUND

Falls commonly occur due to losses of balance associated with vertical body movements (e.g. reacting to uneven ground, street curbs). Research, however, has focused on horizontal perturbations, such as forward and backward translations of the standing surface. This study describes and compares muscle activation patterns following vertical and horizontal perturbations during standing and walking, and investigates the role of vision during standing postural responses.

METHODS

Fourteen healthy participants (ten males; 27±4 years-old) responded to downward, upward, forward, and backward perturbations while standing and walking in a virtual reality (VR) facility containing a moveable platform with an embedded treadmill; participants were also exposed to visual perturbations in which only the virtual scenery moved. We collected bilateral surface electromyography (EMG) signals from 8 muscles (tibialis anterior, rectus femoris, rectus abdominis, external oblique, gastrocnemius, biceps femoris, paraspinals, deltoids). Parameters included onset latency, duration of activation, and activation magnitude. Standing perturbations comprised dynamic-camera (congruent), static-camera (incongruent) and eyes-closed sensory conditions. ANOVAs were used to compare the effects of perturbation direction and sensory condition across muscles.

RESULTS

Vertical perturbations induced longer onset latencies and shorter durations of activation with lower activation magnitudes in comparison to horizontal perturbations (p<0.0001). Downward perturbations while standing generated earlier activation of anterior muscles to facilitate flexion (for example, p=0.0005 and p=0.0021 when comparing the early activators, rectus femoris and tibialis anterior, to a late activator, the paraspinals), whereas upward perturbations generated earlier activation of posterior muscles to facilitate extension (for example, p<0.0001 and p=0.0004, when comparing the early activators, biceps femoris and gastrocnemius, to a late activator, the rectus abdominis). Static-camera conditions induced longer onset latencies (p=0.0085 and p<0.0001 compared to eyes-closed and dynamic-camera conditions, respectively), whereas eyes-closed conditions induced longer durations of activation (p=0.0001 and p=0.0008 compared to static-camera and dynamic-camera, respectively) and larger activation magnitudes. During walking, downward perturbations promptly activated contralateral trunk and deltoid muscles (e.g., p=0.0036 for contralateral deltoid versus a late activator, the ipsilateral tibialis anterior), and upward perturbations triggered early activation of trunk flexors (e.g., p=0.0308 for contralateral rectus abdominis versus a late activator, the ipsilateral gastrocnemius). Visual perturbations elicited muscle activation in 67.7% of trials.

CONCLUSION

Our results demonstrate that vertical (vs. horizontal) perturbations generate unique balance-correcting muscle activations, which were consistent with counteracting vertical body extension induced by downward perturbations and vertical body flexion induced by upward perturbations. Availability of visual input appears to affect response efficiency, and incongruent visual input can adversely affect response triggering. Our findings have clinical implications for the design of robotic exoskeletons (to ensure user safety in dynamic balance environments) and for perturbation-based balance and gait rehabilitation.

The Effects of Powered Exoskeleton Gait Training on Cardiovascular Function and Gait Performance: A Systematic Review

Patients with neurological impairments often experience physical deconditioning, resulting in reduced fitness and health. Powered exoskeleton training may be a successful method to combat physical deconditioning and its comorbidities, providing patients with a valuable and novel experience. This systematic review aimed to conduct a search of relevant literature, to examine the effects of powered exoskeleton training on cardiovascular function and gait performance. Two electronic database searches were performed (2 April 2020 to 12 February 2021) and manual reference list searches of relevant manuscripts were completed. Studies meeting the inclusion criteria were systematically reviewed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. n = 63 relevant titles were highlighed; two further titles were identified through manual reference list searches. Following analysis n = 23 studies were included. Data extraction details included; sample size, age, gender, injury, the exoskeleton used, intervention duration, weekly sessions, total sessions, session duration and outcome measures. Results indicated that exoskeleton gait training elevated energy expenditure greater than wheelchair propulsion and improved gait function. Patients exercised at a moderate-intensity. Powered exoskeletons may increase energy expenditure to a similar level as non-exoskeleton walking, which may improve cardiovascular function more effectively than wheelchair propulsion alone.

Meeting Proceedings for SCI 2020: Launching a Decade of Disruption in Spinal Cord Injury Research

The spinal cord injury (SCI) research community has experienced great advances in discovery research, technology development, and promising clinical interventions in the past decade. To build upon these advances and maximize the benefit to persons with SCI, the National Institutes of Health (NIH) hosted a conference February 12-13, 2019 titled "SCI 2020: Launching a Decade of Disruption in Spinal Cord Injury Research." The purpose of the conference was to bring together a broad range of stakeholders, including researchers, clinicians and healthcare professionals, persons with SCI, industry partners, regulators, and funding agency representatives to break down existing communication silos. Invited speakers were asked to summarize the state of the science, assess areas of technological and community readiness, and build collaborations that could change the trajectory of research and clinical options for people with SCI. In this report, we summarize the state of the science in each of five key domains and identify the gaps in the scientific literature that need to be addressed to move the field forward.

Wearable robotic exoskeleton for gait reconstruction in patients with spinal cord injury: A literature review

Objectives

Wearable robotic exoskeletons (WREs) have been globally developed to achieve gait reconstruction in patients with spinal cord injury (SCI). The present study aimed to enable evidence-based decision-making in selecting the optimal WRE according to residual motor function and to provide a new perspective on further development of appropriate WREs.

Methods

The current review was conducted by searching PubMed, Web of Science, and Google Scholar for relevant studies published from April 2015 to February 2020. Selected studies were analysed with a focus on the participants’ neurological level of SCI, amount of training (number of training sessions and duration of the total training period), gait speed and endurance achieved, and subgroup exploration of the number of persons for assistance and the walking aid used among patients with cervical level injury.

Results

A total of 28 articles (nine using Ekso, three using Indego, ten using ReWalk, one using REX, five using Wearable Power-Assist Locomotor) involving 228 patients were included in the analysis. Across all WREs, T6 was the most frequently reported level of SCI. The amount of training showed a wide distribution (number of training sessions: 2–230 sessions [30–120 min per session]; duration of the total training period: 1–24 weeks [1–5 times per week]). The mean gait speed was 0.31 m/s (standard deviation [SD] 0.14), and the mean distance on the 6-min walking test as a measure of endurance was 108.9 m (SD 46.7). The subgroup exploration aimed at patients with cervical level injury indicated that 59.2% of patients were able to ambulate with no physical assistance and several patients used a walker as a walking aid.

Conclusion

The number of cervical level injury increased, as compared to the number previously indicated by a prior similar review. Training procedure was largely different among studies. Further improvement based on gait performance is required for use and dissemination in daily life.

The translational potential of this article

The present review reveals the current state of the clinical effectiveness of WREs for gait reconstruction in patients with SCI, contributing to evidence-based device application and further development.

Effect of Joint Friction Compensation on a "Muscle-First" Motor-Assisted Hybrid Neuroprosthesis

This study assessed the metabolic energy consumption of walking with the external components of a “Muscle-First” Motor Assisted Hybrid Neuroprosthesis (MAHNP), which combines implanted neuromuscular stimulation with a motorized exoskeleton. The “Muscle-First” approach prioritizes generating motion with the wearer's own muscles via electrical stimulation with the actuators assisting on an as-needed basis. The motorized exoskeleton contributes passive resistance torques at both the hip and knee joints of 6Nm and constrains motions to the sagittal plane. For the muscle contractions elicited by neural stimulation to be most effective, the motorized joints need to move freely when not actively assisting the desired motion. This study isolated the effect of the passive resistance or “friction” added at the joints by the assistive motors and transmissions on the metabolic energy consumption of walking in the device. Oxygen consumption was measured on six able-bodied subjects performing 6 min walk tests at three different speeds (0.4, 0.8, and 1.2 m/s) under two different conditions: one with the motors producing no torque to compensate for friction, and the other having the motors injecting power to overcome passive friction based on a feedforward friction model. Average oxygen consumption in the uncompensated condition across all speeds, measured in Metabolic Equivalent of Task (METs), was statistically different than the friction compensated condition. There was an average decrease of 8.8% for METs and 1.9% for heart rate across all speeds. While oxygen consumption was reduced when the brace performed friction compensation, other factors may have a greater contribution to the metabolic energy consumption when using the device. Future studies will assess the effects of gravity compensation on the muscular effort required to lift the weight of the distal segments of the exoskeleton as well as the sagittal plane constraint on walking motions in individuals with spinal cord injuries (SCI).

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.

Effect of Gait Training Program with Mechanical Exoskeleton on Body Composition of Paraplegics

Purpose

To identify the effect of a 52-weeks gait training program with an exoskeletal body-powered gait orthosis on the body composition of paraplegics.

Patients and Methods

Ten subjects with spinal cord injury at the thoracolumbar spine level for more than 2 years participated and were divided into exercise (n=5) and nonexercise (n=5) groups. A gait training program comprising stages 1–6 with customized exoskeletal body-powered gait orthosis was conducted for 52-weeks. A six-stage gait training program was conducted to manage the body composition and prevent obesity, and the changes in the body composition before and after the program were determined through bioelectrical impedance analysis.

Results

No significant changes in weight, fat-free mass (kg), lean body mass (kg), and percent fat mass (%) are seen in the exercise group before and after the 52-weeks program. However, fat-free mass (pre = 47.3± 6.5, post = 44.3 ± 5.4, kg), lean body mass (pre = 45.2 ± 6.3, post = 42.3±5.2, kg), and percent fat mass (pre = 30.1 ± 12.1, post = 40.9 ± 9.1, kg) show significant changes (p < 0.05) in the nonexercise group. In the nonexercise group, among lean body mass changes over 52-weeks in the upper limbs (−31%), trunks (−9.7%), and lower limbs (−8.6%), upper limbs exhibit the most significant decrease (p < 0.05).

Conclusion

The gait training program with exoskeletal body-powered gait orthosis has a positive effect on fat management in the whole body and lean body mass loss in paraplegics. Furthermore, it is effective in preventing continuous muscle loss and in maintaining health by reducing body fat. Body composition measurements with bioelectrical impedance analysis for paraplegics can be applied in various clinical areas and can be combined with various arbitration methods such as rehabilitation program.

Oxygen Uptake During Exoskeletal-Assisted Walking in Persons With Paraplegia

OBJECTIVE

To determine the cardiometabolic demands associated with exoskeletal-assisted walking (EAW) in persons with paraplegia. This study will further examine if training in the device for 60 sessions modifies cost of transport (CT).

DESIGN

Prospective cohort study. Measurements over the course of a 60-session training program, approximately 20 sessions apart.

SETTING

James J. Peters Bronx Veterans Affairs Medical Center, Center for the Medical Consequences of Spinal Cord Injury Research Center.

PARTICIPANTS

The participants' demographics (N=5) were 37-61 years old, body mass index (calculated as weight in kilograms divided by height in meters squared) of 22.7-28.6, level of injury from T1-T11, and 2-14 years since injury.

INTERVENTIONS

Powered EAW.

MAIN OUTCOME MEASURES

Oxygen consumption per unit time (V˙O₂, mL/min/kg), velocity (m/min), cost of transport (V˙O₂/velocity), and rating of perceived exertion (RPE).

RESULTS

With training: EAW velocity significantly improved (Pre: 51±51m; 0.14±0.14m/s vs Post: 99±42m; 0.28±0.12m/s, P=.023), RPE significantly decreased (Pre: 13±6 vs Post: 7±4, P=.001), V˙O₂ significantly improved (Pre: 9.76±1.23 mL/kg/m vs Post: 12.73±2.30 mL/kg/m, P=.04), and CT was reduced from the early to the later stages of training (3.66±5.2 vs 0.87±0.85 mL/kg/m).

CONCLUSIONS

The current study suggests that EAW training improves oxygen uptake efficiency and walking velocities, with a lower perception of exertion.

Effect of Exoskeletal-Assisted Walking on Soft Tissue Body Composition in Persons With Spinal Cord Injury

OBJECTIVE

To determine the effect of overground walking using a powered exoskeleton on soft tissue body composition in persons with spinal cord injury (SCI).

DESIGN

A prospective, single group observational pilot study.

SETTING

Medical center.

PARTICIPANTS

Persons (N=8) with chronic (>6mo) SCI between 18 and 65 years old who weighed less than 100 kg.

INTERVENTIONS

Overground ambulation training using a powered exoskeleton (ReWalk) for 40 sessions, with each session lasting up to 2 hours, with participants training 3 times per week.

MAIN OUTCOME MEASURE(S)

Dual-energy x-ray absorptiometry (DXA) was used to measure lean mass (LM) and fat mass (FM) from the whole body, arms, legs and trunk. DXA was also used to assess visceral adipose tissue (VAT). Walking performance was measured by 6-minute walk test.

RESULTS

Participants significantly lost total body FM (-1.8±1.2kg, P=.004) with the loss of adiposity distributed over several regional sites. Six of the 8 participants lost VAT, with the average loss in VAT trending toward significance (-0.141kg, P=.06). LM for the group was not significantly changed.

CONCLUSIONS

Sustained and weekly use of powered exoskeletons in persons with SCI has the potential to reduce FM with inferred improvements in health.

Clinician Perceptions of Robotic Exoskeletons for Locomotor Training After Spinal Cord Injury: A Qualitative Approach

OBJECTIVE

To describe the experiences of clinicians who have used robotic exoskeletons in their practice and acquire information that can guide clinical decisions and training strategies related to robotic exoskeletons.

DESIGN

Qualitative, online survey study, and 4 single-session focus groups followed by thematic analysis to define themes.

SETTING

Focus groups were conducted at 3 regional rehabilitation hospitals and 1 Veteran's Administration (VA) Medical Center.

PARTICIPANTS

Clinicians (N=40) reported their demographic characteristics and clinical experience using robotic exoskeletons. Twenty-nine clinicians participated in focus groups at regional hospitals that use robotic exoskeletons, as well as 1 VA Medical Center.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Clinicians' preferences, experiences, training strategies, and clinical decisions on how robotic exoskeleton devices are used with Veterans and civilians with spinal cord injury.

RESULTS

Clinicians had an average of 3 years of experience using exoskeletons in clinical and research settings. Major themes emerging from focus group discussions included appropriateness of patient goals, patient selection criteria, realistic patient expectations, patient and caregiver training for use of exoskeletons, perceived benefits, preferences regarding specific exoskeletons, and device limitations and therapy recommendations.

CONCLUSIONS

Clinicians identified benefits of exoskeleton use including decreased physical burden and fatigue while maximizing patient mobility, increased safety of clinicians and patients, and expanded device awareness and preferences. Suitability of exoskeletons for patients with various characteristics and managing expectations were concerns. Clinicians identified research opportunities as technology continues to advance toward safer, lighter, and hands-free devices.

Exoskeleton home and community use in people with complete spinal cord injury

A consequence of a complete spinal cord injury (SCI) is the loss of gait capacity. Wearable exoskeletons for the lower extremity enable household and community ambulation in people with SCI. This study assessed the amount, purpose, and location of exoskeleton use in the home and community environment, without any restrictions. The number of steps taken was read from the exoskeleton software. Participants kept a daily logbook, and completed two user experience questionnaires (Quebec User Evaluation of Satisfaction with assistive Technology (D-QUEST) and System Usability Scale (SUS)). Fourteen people with a complete SCI used the ReWalk exoskeleton a median of 9 (range [1-15]) out of 16 ([12-21]) days, in which participants took a median of 3,226 ([330-28,882]) steps. The exoskeleton was mostly used for exercise purposes (74%) and social interaction (20%). The main location of use was outdoors (48%). Overall, participants were satisfied with the exoskeleton (D-QUEST 3.7 ± 0.4) and its usability (SUS 72.5 [52.5-95.0]). Participants with complete SCI report satisfaction with the exoskeleton for exercise and social interaction in the home and community, but report limitations as an assistive device during daily life.

Users with spinal cord injury experience of robotic Locomotor exoskeletons: a qualitative study of the benefits, limitations, and recommendations

Background

Persons with spinal cord injury (SCI) may experience both psychological and physiological benefits from robotic locomotor exoskeleton use, and knowledgeable users may have valuable perspectives to inform future development. The objective of this study is to gain insight into the experiences, perspectives, concerns, and suggestions on the use of robotic locomotor exoskeletons by civilians and veterans living with SCI.

Methods

Participants reported their demographic characteristics and the extent of robotic exoskeleton use in an online survey. Then, 28 experienced robotic locomotor exoskeleton users participated in focus groups held at three regional hospitals that specialize in rehabilitation for persons with SCI. We used a qualitative description approach analysis to analyze the data, and included thematic analysis.

Results

Participants expressed that robotic exoskeletons were useful in therapy settings but, in their current form, were not practical for activities of daily living due to device limitations. Participants detailed the psychological benefits of being eye-level with their non-disabled peers and family members, and some reported physiologic improvements in areas such as bowel and bladder function. Participants detailed barriers of increased fatigue, spasticity, and spasms and expressed dissatisfaction with the devices due to an inability to use them independently and safely. Participants provided suggestions to manufacturers for technology improvements.

Conclusions

The varied opinions and insights of robotic locomotor exoskeletons users with SCI add to our knowledge of device benefits and limitations.

Relationships between T-scores at the hip and bone mineral density at the distal femur and proximal tibia in persons with spinal cord injury

Objective: To identify T-score values at the total hip (TH) and femoral neck (FN) that correspond to the cutoff value of <0.60 g/cm² for heightened risk of fracture at the distal femur (DF) and proximal tibia (PT).Design: Retrospective analysis of data in a research center's database. Setting: Community-based individuals with spinal cord injury (SCI). Participants: 105 unique individuals with SCI. Outcome Measurements: DXA derived areal BMD (aBMD) and T-score of the DF, PT, TH, and FN. Results: The aBMD at the DF and PT regions were predictors of T-scores at the TH (R² = 0.63, P < 0.001 and R² = 0.65, P < 0.001) and FN (R² = 0.55, P < 0.001 and R² = 0.58, P < 0.001). Using the DF and PT aBMD of 0.60 g/cm² as a value below which fractures were more likely to occur, the predicted T-score was -3.1 and -3.5 at the TH and -2.6 and -2.9 at the FN, respectively. However, when the predicted and observed T-score values disagree outside the 95% limit of agreement, the predicted T-score values are lower than the measured T-score values, overestimating the measured values between -2.0 and -4.0 SD. Conclusion: The DF and PT cutoff value for aBMD of 0.60 g/cm² was a moderate predictor of T-score values at the TH and FN, with considerable inaccuracies outside the clinically acceptable limits of agreement. As such, the direct measurement of knee aBMD in persons with SCI should be performed, whenever possible, prior to prescribing weight bearing upright activities, such as robotic exoskeletal-assisted walking.

Safety and feasibility of exoskeleton-assisted walking during acute/sub-acute SCI in an inpatient rehabilitation facility: A single-group preliminary study

Context/objective: Information on the safety and feasibility of lower extremity powered exoskeletons for persons with acute/sub-acute spinal cord injury (SCI) is limited. Understanding the safety and feasibility of employing powered exoskeletons in acute/sub-acute (<6 months post injury) at a SCI acute inpatient rehabilitation (SCI-AIR) facility could guide clinical practice and provide a basis for larger clinical trials on efficacy and effectiveness. Design: Single group observational study. Setting: SCI-AIR. Participants: Participants (n = 12; age: 28-71 years; 58% AIS D; 58% male) with neurological levels of injuries ranging from C2 to L3. Interventions: Up to 90 min of exoskeleton-assisted locomotor training was provided up to three times per week during SCI-AIR. Outcome measures: Safety of device use during inpatient locomotor training was quantified as the number of adverse events (AE) per device exposure hour. Feasibility of device use was defined in terms of protocol compliance, intensity, and proficiency. Results: Concerning safety, symptomatic hypotension was the most common AE reported at 111-events/exoskeleton-hours. Protocol compliance had a mean (SD) of 54% (30%). For intensity, 77% of participants incorporated variable assistance into at least 1 walking session; 70% of participants' sessions were completed with a higher RPE than the physical therapist. In proficiency, 58% achieved at least minimal assistance when walking with the device. Conclusion: Exoskeleton training in SCI-AIR can be safe and feasible for newly injured individuals with SCI who have clinically defined ambulatory goals. Nonetheless, sufficient controls to minimize risks for AEs, such as hypotensive events, are required.

Mobility Skills With Exoskeletal-Assisted Walking in Persons With SCI: Results From a Three Center Randomized Clinical Trial

Background: Clinical exoskeletal-assisted walking (EAW) programs for individuals with spinal cord injury (SCI) have been established, but many unknown variables remain. These include addressing staffing needs, determining the number of sessions needed to achieve a successful walking velocity milestone for ambulation, distinguishing potential achievement goals according to level of injury, and deciding the number of sessions participants need to perform in order to meet the Food and Drug Administration (FDA) criteria for personal use prescription in the home and community. The primary aim of this study was to determine the number of sessions necessary to achieve adequate EAW skills and velocity milestones, and the percentage of participants able to achieve these skills by 12 sessions and to determine the skill progression over the course of 36 sessions.

Methods: A randomized clinical trial (RCT) was conducted across three sites, in persons with chronic (≥6 months) non-ambulatory SCI. Eligible participants were randomized (within site) to either the EAW arm first (Group 1), three times per week for 36 sessions, striving to be completed in 12 weeks or the usual activity arm (UA) first (Group 2), followed by a crossover to the other arm for both groups. The 10-meter walk test seconds (s) (10MWT), 6-min walk test meters (m) (6MWT), and the Timed-Up-and-Go (s) (TUG) were performed at 12, 24, and 36 sessions. To test walking performance in the exoskeletal devices, nominal velocities and distance milestones were chosen prior to study initiation, and were used for the 10MWT (≤ 40s), 6MWT (≥80m), and TUG (≤ 90s). All walking tests were performed with the exoskeletons.

Results: A total of 50 participants completed 36 sessions of EAW training. At 12 sessions, 31 (62%), 35 (70%), and 36 (72%) participants achieved the 10MWT, 6MWT, and TUG milestones, respectively. By 36 sessions, 40 (80%), 41 (82%), and 42 (84%) achieved the 10MWT, 6MWT, and TUG criteria, respectively.

Conclusions: It is feasible to train chronic non-ambulatory individuals with SCI in performance of EAW sufficiently to achieve reasonable mobility skill outcome milestones.

Locomotor training in people with spinal cord injury: is this exercise?

Locomotor training holds tremendous appeal to people with spinal cord injury who are wheelchair dependent, as the reacquisition of gait remains one of the most coveted goals in this population. For the last few decades this type of training has remained primarily in the clinical environment, as it requires the use of expensive treadmills with bodyweight support or complex overhead suspension tracks to facilitate overground walking. The development of powered exoskeletons has taken locomotor training out of the clinic, both improving accessibility and providing a potential option for community ambulation in people with lower limb paralysis. A question that has yet to be answered, however, is whether or not locomotor training offers a sufficiently intense stimulus to induce improvements in fitness or health. As inactivity-related secondary health complications are a major source of morbidity and mortality in people with SCI, it would be important to characterize the potential of locomotor training to not only improve functional walking ability, but also improve health-related fitness. This narrative review will summarize the key literature in this area to determine whether locomotor training challenges the cardiovascular, muscular or metabolic systems enough to be considered a viable form of exercise.

Energy Efficiency and Patient Satisfaction of Gait With Knee-Ankle-Foot Orthosis and Robot (ReWalk)-Assisted Gait in Patients With Spinal Cord Injury

OBJECTIVE

To compare the energy efficiency of gait with knee-ankle-foot orthosis (KAFO) and robot-assisted gait and to develop a usability questionnaire to evaluate the satisfaction of walking devices in paraplegic patients with spinal cord injuries.

METHODS

Thirteen patients with complete paraplegia participated and 10 completed the evaluation. They were trained to walk with KAFO (KAFO-gait) or a ReWalk robot (ReWalk-gait) for 4 weeks (20 sessions). After a 2-week wash-out period, they switched walking devices and underwent 4 additional weeks of training. Two evaluations were performed (after 2 and 4 weeks) following the training periods for each walking device, using the 6-minute walking test (6MWT) and 30-minute walking test (30MWT). The spatiotemporal variables (walking distance, velocity, and cadence) and energy expenditure (heart rate, maximal heart rate, the physiologic cost index, oxygen consumption, metabolic equivalents, and energy efficiency) were evaluated duringthe 6MWT and 30MWT. A usability evaluation questionnaire for walking devices was developed based on the International Organization for Standardization/International Electrotechnical Commission guidelines through expert consultation.

RESULTS

The ReWalk-gait presented significant advantages in energy efficiency compared to KAFO-gait in the 6MWT and 30MWT; however, there were no differences in walking distance or speed in the 30MWT between ReWalk-gait and KAFOgait. The usability test demonstrated that ReWalk-gait was not superior to KAFO-gait in terms of safety, efficacy, efficiency, or patient satisfaction.

CONCLUSION

The robot (ReWalk) enabled patients with paraplegia to walk with lower energy consumption compared to KAFO, but the ReWalk-gait was not superior to KAFO-gaitin terms of patient satisfaction.

Appraisals of robotic locomotor exoskeletons for gait: focus group insights from potential users with spinal cord injuries

Purpose: To describe appraisals of robotic exoskeletons for locomotion by potential users with spinal cord injuries, their perceptions of device benefits and limitations, and recommendations for manufacturers and therapists regarding device use.Materials and methods: We conducted focus groups at three regional rehabilitation hospitals and used thematic analysis to define themes.Results: Across four focus groups, 35 adults participated; they were predominantly middle-aged, male, and diverse in terms of race and ethnicity, well educated, and not working. Participants had been living with SCI an average of two decades. Most participants were aware of exoskeletons. Some were enthusiastic about the usability of the devices while others were more circumspect. They had many questions about device affordability and usability, and were discerning in their appraisal of benefits and suitability to their particular circumstances. They reflected on device cost, the need for caregiver assistance, use of hands, and environmental considerations. They weighed the functional benefits relative to the cost of preferred activities. Their recommendations focused on cost, battery life, and independent use.Conclusions: Potential users' appraisals of mobility technology reflect a nuanced appreciation of device costs; functional, social, and psychological benefits; and limitations. Results provide guidance to therapists and manufacturers regarding device use.Implications for RehabilitationPotential users of robotic locomotor exoskeletons with spinal cord injuries appreciate the functional, social, and psychological benefits that these devices may offer.Their appraisals reflect nuanced consideration of device cost and features, and the suitability of the assistive technology to their circumstances.They recommend that manufacturers focus on reducing cost, extending battery life, and features that allow independent use.

Exoskeletal-Assisted Walking During Acute Inpatient Rehabilitation Leads to Motor and Functional Improvement in Persons With Spinal Cord Injury: A Pilot Study

OBJECTIVE

To explore the potential effects of incorporating exoskeletal-assisted walking (EAW) into spinal cord injury (SCI) acute inpatient rehabilitation (AIR) on facilitating functional and motor recovery when compared with standard of care AIR.

DESIGN

A quasi-experimental design with a prospective intervention group (AIR with EAW) and a retrospective control group (AIR only).

SETTING

SCI AIR facility.

PARTICIPANTS

Ten acute inpatient participants with SCI who were eligible for locomotor training were recruited in the intervention group. Twenty inpatients with SCI were identified as matched controls by reviewing an AIR database, Uniform Data System for Medical Rehabilitation, by an individual blinded to the study. Both groups (N=30) were matched based on etiology, paraplegia/tetraplegia, completeness of injury, age, and sex.

INTERVENTION

EAW incorporated into SCI AIR.

MAIN OUTCOME MEASURES

FIM score, International Standards for Neurological Classification of Spinal Cord Injury Upper Extremity Motor Score and Lower Extremity Motor Scores (LEMS), and EAW session results, including adverse events, walking time, and steps.

RESULTS

Changes from admission to discharge LEMS and FIM scores were significantly greater in the intervention group (LEMS change: 14.3±10.1; FIM change: 37.8±10.8) compared with the control group (LEMS change: 4.6±6.1; FIM change: 26.5±14.3; Mann-Whitney U tests: LEMS, P<.01 and FIM, P<.05). One adverse event (minor skin abrasion) occurred during 42 walking sessions. Participants on average achieved 31.5 minutes of up time and 18.2 minutes of walk time with 456 steps in one EAW session.

CONCLUSIONS

Incorporation of EAW into standard of care AIR is possible. AIR with incorporated EAW has the potential to facilitate functional and motor recovery compared with AIR without EAW.

Changes in bowel function following exoskeletal-assisted walking in persons with spinal cord injury: an observational pilot study

Study Design

Prospective, observational study

Objective

To explore the effects of exoskeleton-assisted walking (EAW) on bowel function in persons with spinal cord injury (SCI).

Setting

Ambulatory research facility located in a tertiary care hospital

Methods

Individuals 18–65 years of age, with thoracic vertebrae one (T1) to T11 motor-complete paraplegia of at least 12 months duration were enrolled. Pre- and post-EAW training, participants were asked to report on various aspects of their bowel function as well as on their overall quality of life (QOL) as related to their bowel function.

Results

Ten participants completed 25–63 sessions of EAW over a period of 12 to 14 weeks, one participant was lost to follow up due to early withdrawal after 10 sessions. Due to the small sample size, each participant’s results were presented descriptively in a case series format. At least 5/10 participants reported improvements with frequency of bowel evacuations, less time spent on bowel management per bowel day, fewer bowel accidents per month, reduced laxative and/or stool softener use, and improved overall satisfaction with their bowel program post-EAW training. Furthermore, 8/10 reported improved stool consistency and 7/10 reported improved bowel function related QOL. One participant reported worsening of bowel function post-EAW.

Conclusion

Between 50 and 80% of the participants studied reported improvements in bowel function and/or management post-EAW training. EAW training appeared to mitigate SCI-related bowel dysfunction and the potential benefits of EAW on bowel function after SCI is worthy or further study.

Sponsorship

N/A

Cardiopulmonary function after robotic exoskeleton-assisted over-ground walking training of a patient with an incomplete spinal cord injury: Case report

RATIONALE

Spinal cord injury (SCI) patients who experience difficulties with independent walking use gait-assistive devices such as a cane, walker, or wheelchair. Few studies have explored gait patterns or cardiopulmonary function in chronic SCI patients after powered exoskeleton training. We investigated whether the cardiopulmonary function of a patient with an incomplete chronic cervical SCI and a hemiplegic gait pattern could be improved by walking training using a powered exoskeleton (Angelegs).

PATIENT CONCERNS

A 57-year-old male was diagnosed with an SCI at C3-C4. The right upper and lower limb motor functions differed when evaluated before entry into the program. Motor function was good in the right leg but poor in the left one. Before program entry, the patient could walk for about 10 m using a cane. He did not have a history of severe medical or psychological problems and was not cognitively impaired.

DIAGNOSIS

The patient was tetraplegia with incomplete SCI at C3-C4.

INTERVENTIONS

The patient was trained for 6 weeks using a powered exoskeleton. The training program consisted of sit-to-stand and stand-to-sit movements, maintenance of balanced standing for 5 minutes, and walking for 15 minutes.

OUTCOMES

After 6 weeks of training, gait speed improved in the timed up-and-go test, and cardiac function was enhanced as measured by the metabolic equivalent and VO2 tests.

LESSIONS

Walking training using a powered exoskeleton can facilitate the effective rehabilitation and improve the gait speed and cardiopulmonary function of patients with chronic SCIs or strokes.

Retraining walking over ground in a powered exoskeleton after spinal cord injury: a prospective cohort study to examine functional gains and neuroplasticity

Background

Powered exoskeletons provide a way to stand and walk for people with severe spinal cord injury. Here, we used the ReWalk exoskeleton to determine the training dosage required for walking proficiency, the sensory and motor changes in the nervous system with training, and the functionality of the device in a home-like environment.

Methods

Participants with chronic (> 1 yr) motor complete or incomplete spinal cord injury, who were primarily wheelchair users, were trained to walk in the ReWalk for 12 weeks. Measures were taken before, during, immediately after, and 2–3 months after training. Measures included walking progression, sitting balance, skin sensation, spasticity, and strength of the corticospinal tracts.

Results

Twelve participants were enrolled with 10 completing training. Training progression and walking ability: The progression in training indicated about 45 sessions to reach 80% of final performance in training. By the end of training, participants walked at speeds of 0.28–0.60 m/s, and distances of 0.74–1.97 km in 1 h. The effort of walking was about 3.3 times that for manual wheelchair propulsion. One non-walker with an incomplete injury became a walker without the ReWalk after training. Sensory and motor measures: Sitting balance was improved in some, as seen from the limits of stability and sway speed. Neuropathic pain showed no long term changes. Change in spasticity was mixed with suggestion of differences between those with high versus low spasticity prior to training. The strength of motor pathways from the brain to back extensor muscles remained unchanged. Adverse events: Minor adverse events were encountered by the participants and trainer (skin abrasions, non-injurious falls). Field testing: The majority of participants could walk on uneven surfaces outdoors. Some limitations were encountered in home-like environments.

Conclusion

For individuals with severe SCI, walking proficiency in the ReWalk requires about 45 sessions of training. The training was accompanied by functional improvements in some, especially in people with incomplete injuries.

Trial registration

NCT02322125 Registered 22 December 2014.

Electronic supplementary material

The online version of this article (10.1186/s12984-019-0585-x) contains supplementary material, which is available to authorized users.

Bone Mineral Density Testing in Spinal Cord Injury: 2019 ISCD Official Position

Spinal cord injury (SCI) causes rapid osteoporosis that is most severe below the level of injury. More than half of those with motor complete SCI will experience an osteoporotic fracture at some point following their injury, with most fractures occurring at the distal femur and proximal tibia. These fractures have devastating consequences, including delayed union or nonunion, cellulitis, skin breakdown, lower extremity amputation, and premature death. Maintaining skeletal integrity and preventing fractures is imperative following SCI to fully benefit from future advances in paralysis cure research and robotic-exoskeletons, brain computer interfaces and other evolving technologies. Clinical care has been previously limited by the lack of consensus derived guidelines or standards regarding dual-energy X-ray absorptiometry-based diagnosis of osteoporosis, fracture risk prediction, or monitoring response to therapies. The International Society of Clinical Densitometry convened a task force to establish Official Positions for bone density assessment by dual-energy X-ray absorptiometry in individuals with SCI of traumatic or nontraumatic etiology. This task force conducted a series of systematic reviews to guide the development of evidence-based position statements that were reviewed by an expert panel at the 2019 Position Development Conference in Kuala Lumpur, Malaysia. The resulting the International Society of Clinical Densitometry Official Positions are intended to inform clinical care and guide the diagnosis of osteoporosis as well as fracture risk management of osteoporosis following SCI.

Experience of Robotic Exoskeleton Use at Four Spinal Cord Injury Model Systems Centers

BACKGROUND AND PURPOSE

Refinement of robotic exoskeletons for overground walking is progressing rapidly. We describe clinicians' experiences, evaluations, and training strategies using robotic exoskeletons in spinal cord injury rehabilitation and wellness settings and describe clinicians' perceptions of exoskeleton benefits and risks and developments that would enhance utility.

METHODS

We convened focus groups at 4 spinal cord injury model system centers. A court reporter took verbatim notes and provided a transcript. Research staff used a thematic coding approach to summarize discussions.

RESULTS

Thirty clinicians participated in focus groups. They reported using exoskeletons primarily in outpatient and wellness settings; 1 center used exoskeletons during inpatient rehabilitation. A typical episode of outpatient exoskeleton therapy comprises 20 to 30 sessions and at least 2 staff members are involved in each session. Treatment focuses on standing, stepping, and gait training; therapists measure progress with standardized assessments. Beyond improved gait, participants attributed physiological, psychological, and social benefits to exoskeleton use. Potential risks included falls, skin irritation, and disappointed expectations. Participants identified enhancements that would be of value including greater durability and adjustability, lighter weight, 1-hand controls, ability to navigate stairs and uneven surfaces, and ability to balance without upper extremity support.

DISCUSSION AND CONCLUSIONS

Each spinal cord injury model system center had shared and distinct practices in terms of how it integrates robotic exoskeletons into physical therapy services. There is currently little evidence to guide integration of exoskeletons into rehabilitation therapy services and a pressing need to generate evidence to guide practice and to inform patients' expectations as more devices enter the market.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A231).

Differences in Acute Metabolic Responses to Bionic and Nonbionic Ambulation in Spinal Cord Injured Humans and Controls

OBJECTIVES

To (1) compare energy expenditure during seated rest, standing, and prolonged bionic ambulation or bipedal ambulation in participants with spinal cord injury (SCI) and noninjured controls, respectively, and (2) test effects on postbionic ambulation glycemia in SCI.

DESIGN

Two independent group comparison of SCI and controls.

SETTING

Academic Medical Center.

PARTICIPANTS

Ten participants with chronic SCI (C7-T1, American Spinal Injury Association Impairment Scale A-C) and 10 controls (N=20).

INTERVENTIONS

A commercial bionic exoskeleton.

MAIN OUTCOME MEASURES

Absolute and relative (to peak) oxygen consumption, perceived exertion, carbohydrate/fat oxidation, energy expenditure, and postbionic ambulation plasma glucose/insulin.

RESULTS

Average work intensity accompanying 45 minutes of outdoor bionic ambulation was <40% peak oxygen consumption, with negligible drift after reaching steady state. Rating of perceived exertion (RPE) did not differ between groups and reflected low exertion. Absolute energy costs for bionic ambulation and nonbionic ambulation were not different between groups despite a 565% higher ambulation velocity in controls and 3.3× higher kilocalorie per meter in SCI. Fuel partitioning was similar between groups and the same within groups for carbohydrate and fat oxidation. Nonsignificant (9%) lowering of the area under a glucose tolerance curve following bionic ambulation required 20% less insulin than at rest.

CONCLUSION

Work intensity during prolonged bionic ambulation for this bionic exoskeleton is below a threshold for cardiorespiratory conditioning but above seated rest and passive standing. Bionic ambulation metabolism is consistent with low RPE and unchanged fuel partitioning from seated rest. Bionic ambulation did not promote beneficial effects on glycemia in well-conditioned, euglycemic participants. These findings may differ in less fit individuals with SCI or those with impaired glucose tolerance. Observed trends favoring this benefit suggest they are worthy of testing.

Perspectives of people with spinal cord injury learning to walk using a powered exoskeleton

BACKGROUND

Powered exoskeletons for over ground walking were designed to help people with neurological impairments to walk again. Extended training in powered exoskeletons has led to changes in walking and physiological functions. Few studies have considered the perspective of the participants. The users' perspective is vital for adoption of assistive devices. We explored the expectations and experiences of persons with spinal cord injury, training with the ReWalk exoskeleton.

METHODS

A qualitative research design with individual interviews was used. Eleven participants with spinal cord injury, taking part in 12 weeks of 4 times weekly training using the ReWalk, were interviewed before, immediately after, and 2 months after training. Interviews were audio recorded and transcribed verbatim. A six stage approach to thematic analysis was used.

RESULTS

The theme consistently expressed was the exoskeleton allowed participants to do everyday activities, like everyone else, such as looking people in the eye or walking outside. Their experiences were captured in three categories: 1) learning, a description of both expectations for learning and perspectives on how learning occurred; 2) changing, perspectives on perceived changes with training; and 3) contributing, which captured participant perspectives on contributing to research, including the giving of direct feedback regarding the exoskeleton (i.e., what worked and what could be changed).

CONCLUSIONS

Incorporating the view of the user in the design and refinement of exoskeletons will help ensure that the devices are appropriate for future users. Availability and support for the use of exoskeleton devices in community settings is an interim step to home use as the devices continue to improve.

TRIAL REGISTRATION

www.clinicaltrials.gov ( NCT02322125 ). Registered Dec 22, 2014 - Retrospectively registered after the first 4 participants had enrolled in the study.