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NEURO-REHABILITATION SUPPLEMENT
Year : 2023 | Volume
: 26
| Issue : 7 | Page : 26-31
Gait training with robotic exoskeleton assisted rehabilitation system in patients with incomplete traumatic and non-traumatic spinal cord injury: A pilot study and review of literature
Anupam Gupta, Naveen B Prakash, Preethi R Honavar
Department of Neurological Rehabilitation, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
Correspondence Address:
Anupam Gupta
Department of Neurological Rehabilitation, National Institute of Mental Health and Neuro-Sciences (NIMHANS), Bengaluru, Karnataka
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/aian.aian_1075_21
Abstract
Objective: This pilot study aimed to assess the safety and feasibility of robotic gait training and its' effects on gait parameters in individuals with incomplete motor spinal cord injury-SCI (AIS C and AIS D). Methods: The study was conducted in a tertiary research center with indigenously developed Robotic Exoskeleton Assisted Rehabilitation Systems (REARS). Primary outcome measures used were the ten-meter walk test (10MWT), two-minute walk test (2MWT), six-minute walk test (6MWT), the timed up and go test (TUG), the walking index for spinal cord injury II (WISCI II), and the spinal cord independence measure version III (SCIM III) at baseline, 12 sessions, and after 24 sessions (endpoint) of training. At baseline, individuals who could not perform 10MWT, TUG, and 6MWT were grouped in G1 for analysis. Participants in G2 were able to perform all the tests at baseline. Results: The median (interquartile range [IQR]) age and duration of illness was 41 (24) years and 167 (147) days, respectively. Five out of seven participants had non-traumatic etiology and five were males. After completing training, participants in G1 were able to complete the 10MWT, 6MWT, and TUG, and the mean (SD) scores were 0.2 m/s (0.2), 66.3 m (61.2) and 113.3 s (117.4), respectively. Participants in G2 could perform the TUG test 13.5 s faster at the end of the study (11.9 s vs 25.4 s). The minimum clinically important difference (MCID) for TUG was 10.8 s. In G2, the pre-post training change in mean score of 10MWT and 6MWT was 0.11 m/s and 42 m, respectively; these values approached the MCID for these measures. None of the participants had any injury during training. Conclusions: Robotic gait training with REARS is safe and feasible. Such training may lead to an improvement in balance and walking capacity.
Keywords: Exoskeleton robot, gait training, incomplete spinal cord injury, locomotion
Introduction 
Traumatic and non-traumatic spinal cord injuries (SCI) or dysfunction cause sensory and motor function impairments in affected patients and result in long-term disability.[1] The quality of life in SCI patients is directly related to the level of physical activity, and achieving mobility is a felt need in this population, which is influenced by the neurological and functional recovery.[2],[3],[4]
Gait training involves repeated movements based on the principles of motor learning and may lead to better motor control and coordination in the limbs with walking.[5] There have been rapid technological advancements in the field of neuro-engineering and neurorehabilitation in the last three decades. Body weight–supported treadmill training (BWSTT) is one such example which has been used for gait training of SCI individuals in the past. It uses a harness for partial un-weighing and a treadmill for ambulation. The lower limbs are assisted/supported by a therapist(s).[6] Robotic gait training has been a more recent advent used for gait training in SCI. Gait robots aid in improving mobility status, reduce fatigue, increase motivation, provide better motor control, feedback and mechanical movements, and expedite the rehabilitation process.[7],[8],[9] Overground gait training with robotic exoskeleton (Ekso, Ekso Bionics; ReWalk, Indego Robotics) is also feasible in individuals with SCI.[10],[11] Long-term wheelchair users have reported satisfaction with gait training without concerns related to complications with the use of the device.[12] Barriers to gait training with robotic device during in-patient rehabilitation have to be removed to enable access to the services and improve functional status.[13],[14]
Untethered exoskeletons like ReWalk, Indego, etc., are wearable, powered, and articulated suits with self-contained power sources and control algorithms that allow for the freedom and realistic walking experience. The disadvantage is that the patient must carry the heavy weight of the power source on their back. Another major disadvantage is that patients with poor trunk control cannot use these devices for gait training.
Robotic Exoskeleton Assisted Rehabilitation Systems (REARS) is a robotic device with an exoskeletal system developed by an Indian start-up Bionic Yantra. It is a state-of-the-art robotic system that is intended to provide a comprehensive rehabilitation therapy to individuals with SCI and other neurological disorders like stroke and head injury. The device has two parts: (1) A body weight support system which is a mobile robot for overground walking and balance training; and (2) a powered exoskeleton called the wearable robot [Figure 1].
This device has all the advantages of untethered exoskeletons along with a support frame that provides fall safety. Additionally, the heavy power source is embedded in the frame so that the patient does not have to carry the extra weight and can be trained for walking for a longer period of time without fatigue. The disadvantage is that the patient can ambulate only in a controlled environment, like a gait laboratory, and community ambulation is not feasible.
The novelty of the study is that this is the first robotic gait trainer manufactured by an Indian start-up, so the price would be comparatively affordable by different institutes in the country with limited resources. Engineering support required for upkeep of the equipment would be easily available. This gait trainer provides an opportunity to the patients to actually do overground walking, unlike the previously available technology with which the patients would walk on a treadmill.
This pilot study aimed to assess the safety and feasibility of gait training in individuals with incomplete SCI (both traumatic and non-traumatic) with REARS and to observe improvement in gait parameters after training.
Patients and Methods Recruitment of the patients
This prospective study was conducted in a tertiary research and teaching hospital in India. The trial was approved by the Institutional Ethics Committee and was registered with the Clinical Trial Registry of India (CTRI/2020/10/028328). Adult men and women with tetraplegia or paraplegia who were in-patients in the neurorehabilitation unit and aged between 18 and 60 years were screened; eligible patients who gave their informed consent were recruited in the study. All the participants underwent a detailed neurological examination at the time of admission.
Individuals who weighed less than 90 kg, whose height measured between 5 and 6 feet, and who were diagnosed with incomplete motor spinal cord injury AIS C and D ([ASIA: American Spinal Injury Association] Impairment Scale [AIS]) were included.[15] Patients with injury or dysfunction duration of ≥3 weeks, single breath count ≥30, no dyspnea on exercise and no history of other chronic neurological conditions were included. Pregnant women, SCI with AIS A or B, uncontrolled hypertension or severe orthostatic hypotension that limited standing, uncontrolled autonomic dysreflexia, recent myocardial infarction (last 6 months) or uncontrolled cardiac arrhythmia, active infection, pressure ulcers which might have come into contact with the exoskeleton, active heterotopic ossification, contractures at the hip/knee or any hip/knee axis abnormalities that prevented standing, unresolved deep venous thrombosis, people with colostomy, cognitive impairment that interfered with communication of pain and inability to understand two-step commands, or those involved concomitantly in another interventional study were excluded.
Gait training with REARS
Personnel involved in operating the device were trained by an authorized engineer of the equipment manufacturer (Bionic Yantra, Bengaluru, India).
The first session with the robotic system was to familiarize the patients with SCI with the device. The patient's comfort with the device, ability to tolerate the harness and walk for one hour (with or without rest in between) was the focus of session 0. This was followed by 24 sessions of gait training with REARS, each session lasting for one hour that included periods of rest, with about 5 to 6 training sessions in one week. Gait training was conducted by the same physiotherapist. The participants underwent one hour of occupational therapy each day, which included training in transfers, trunk and pelvic balance, upper extremity range-of-motion exercises, hand function, grip strengthening, and activities of daily living. Psychosocial issues like family and emotional support, and coping skills with anxiety and low mood or depression were addressed by psychologists and social workers during the in-patient rehabilitation. The outcomes were measured at the beginning of training (baseline), after 12 sessions (midpoint), and after 24 sessions of gait training (endpoint). Outcomes of all of the participants were measured by the same individual.
REARS device
The device consists of two parts, namely, a body weight support system, which is a mobile robot (MR), and a powered wearable exoskeleton (PE). The structure of the MR is like a frame which is about two meter in height with electronically powered wheels for either backward or forward motion and castor wheels for turning [Figure 1]. It has a harness, which is used for supporting the person, and a winch, which aids in constant unloading of a portion of the participant's body weight. The MR has sensors to monitor the participant's center of gravity, load, position, acceleration, and the intent to move. If there is any sign of a sudden fall, it would immediately be detected by the sensors and the device would stop. The MR can move alongside the participant while walking. The PE is a robotic brace for the lower limbs; it has motors at the hips and knees for locomotion in a pre-set, fixed gait pattern. The manufacturer processed gait data of able-bodied individuals and normalized it to fit the parameters of individuals with SCI. Based on anthropometric data, the width of the metal waist band and the length of the thigh piece and leg can be adjusted in the PE. There are pads with Velcro to accommodate different thigh and calf girth and to ensure adequate immobilization at the knee and ankle joints.
The participant's vitals were recorded before and after each session. Injury severity was graded using the International Standards for Classification after Spinal Cord Injury by the American Spinal Injury Association (ASIA).[15]
Outcome measures
The primary outcome measures used in the study were the ten-meter walk test (10MWT) to assess gait speed; the two-minute walk test (2MWT) and six-minute walk test (6MWT) to assess endurance; the timed up and go test (TUG) to assess balance; the walking index for spinal cord injury II (WISCI II) to assess walking ability; and the spinal cord independence measure version III (SCIM III) to assess the functionality of the individuals with SCI. These outcome measures have been used in this population in a number of studies in the past.[16] The 10MWT, 2MWT, and 6MWT were recorded making the participants walk overground without the use of exoskeleton, and they were allowed to use an assistive device but no support from another person during the tests.
Spasticity was graded using the modified Ashworth scale (MAS) and muscle strength was examined using modified Medical Research Council (mMRC) scale. After each session, a thorough examination was conducted to look for any skin abrasion, redness, pain, or discomfort anywhere in the limbs or trunk that might have been caused by the components of the device. Any falls, skin breakdown, and pain during the training sessions were recorded. Additionally, any device malfunction was also recorded.
Data analysis
The demographic baseline characteristics of the participants were analyzed using median (interquartile range [IQR]) for continuous data and using frequency and percentage for categorical data. The minimum clinically important difference (MCID) values of the outcome scores were used for analysis of gait parameters.
Results This was the pilot phase of the study with seven SCI patients consisting of five (71%) males. The median (IQR) age of the participants was 41 (24) years. The median (IQR) duration of illness at the start of training was 167 (33) days. Five (71%) patients had non-traumatic etiology, four patients had thoracic lesion with paraplegia, and three cervical lesion with tetraplegia. At the time of recruitment for the study, four participants were AIS C and three were AIS D. One individual dropped out of the study after completion of 6 sessions; however, the baseline data was included in the analysis. The demographic characteristics of the participants are shown in [Table 1].
Of the seven particiapnts, thee were not able to perform the 10MWT, TUG, and 6MWT at the beginning of the study; their data were grouped together for analysis (G1). The mean (SD) upper and lower extremity motor scores in G1 at baseline were 43 (12) and 16.3 (11.9), respectively (out of a maximum score of 50 for upper limbs and 50 for lower limbs). The participants' mean (SD) scores at the onset of the study using WISCI II and SCIM III were 4.3 (2.9) and 42.7 (18.6), respectively.
Three individuals who were able to perform 10MWT and 2MWT were grouped (G2) for analysis. One participant was able to perform 10MWT and TUG but not 6MWT at baseline: the data from this individual was excluded. In G2, at the time of admission, mean (SD) upper and lower extremity motor scores were 36 (16.4) and 23.3 (2.5), respectively. At baseline, mean (SD) scores on 10MWT, TUG, and 6MWT were 0.69 m/s (0.04), 14.6 s (1.1), and 253.7 m (79.7), respectively. The mean (SD) scores at baseline in WISCI II was 19 (1.7) and SCIM III was 83.7 (14.6). The data recorded at various time-points in the study are depicted in [Table 2].
Table 2: Comparison of Outcome Measures at the Beginning and End of the Study Discussion The robotic devices for gait training can be divided into overground or stationary systems.[17] The latter has a rigid frame with a harness for providing body support and can either be a tethered exoskeleton in which the robotic device is attached to the user's lower limbs and the treadmill acts as a movable platform (e.g., Locomat, Hocoma, Switzerland; ReoAmbulator, Motorika, New Jersey, USA; LOPES, University of Twente, Netherlands) or an end effector device which has movable foot plates and the proximal joints are moved based on the movement of the foot plates (e.g., G-EO systems, Rhea Technologies, Switzerland; Gait Trainer GT II, Reha-Stim, Germany).[17],[18] Overground robotic systems may either be untethered exoskeletons or patient-guided devices. The untethered exoskeletons are wearable devices that consist of power sources and motors, and they allow people to move on their own; however, the user has to carry a heavy power source on their back (e.g., Indego, Parker Hannefin Corp, Ohio, USA; ReWalk, ReWalk Robotics, USA; Ekso, Ekso Bionics, USA). The patient-guided devices have a rigid construct, provide support through the harness, and contain sensors to detect motion, thereby moving along with the person as they generate the required stimulus (Andago, Hocoma AG, Switzerland).[17],[18] There is also a hybrid system used for gait training in which the movement of the exoskeleton occurs, taking into consideration voluntary movement of the limb, or it makes use of the autonomous mode, which senses a change of pressure in the foot or shifting of weight to initiate and continue the gait cycle.[19]
Robotic exoskeletons can be used for gait training in the outpatient department. Although the robotic device constructs are different and there is variation in study protocols, literature for the potential benefits of training with a robotic exoskeleton has been accumulating.[20],[21] Individuals with traumatic or non-traumatic SCI have reported relief from pain and spasticity after overground training with a robotic device and adequate subjective acceptance.[22] Another study with chronic SCI reported reduction in fat, and increase in lean body mass and bone mineral density at the knee after gait training with a robotic device.[23] Reduction in cost of gait training, improvement in pulmonary functions, reduction in urinary incontinence, and improvement in filling and voiding phase parameters during urodynamics have also been reported.[24],[25],[26]
In the present study, we had more participants with non-traumatic SCI, but good neurological and functional recovery in both traumatic and non-traumatic SCI groups were observed, which is a consistent trend.[27],[28] A previous study reported better endurance after body weight–supported overground training with functional electrical stimulation than treadmill-based robotic gait training alone in chronic incomplete SCIs (AIS C/D), with a similar effect on walking speed (improved with both the approaches).[29] A higher level of trunk muscle activation (as recorded by electromyography) was seen with overground training (Ekso Bionics) in comparison to a treadmill-based approach.[30]
REARS is an overground training device that requires participants to initiate movement of the trunk and pelvis, which is detected by sensors that trigger the movement of the mobile robot and exoskeleton and may aid in improving balance. In the present study, we observed an improvement in TUG scores in all participants (G1 and G2). A study in the center that observed the role of virtual reality in SCI reported improvement in balance parameters.[31] We plan to use virtual reality along with REARS to study their concomitant effect on posture in the SCI population.
Studies have been published on assessment of walking speed of patients wearing exoskeletons, but in the present study, assessment of walking speed and other gait parameters were recorded with overground walking without the use of exoskeleton.[32],[33] Based on the initial ability to walk, we stratified individuals into two groups (G1 and G2) for analysis, which has been reported in one previous study as well.[34] Individuals with SCI with better walking speed took lesser time to complete the TUG test, walked more during 6MWT, and had greater improvement of functional mobility after training in our study. Similar findings with training on a robotic device have been reported.[34] A meta-analysis of three trials on individuals with SCI who underwent robotic gait training reported similar change in walking speed but no change in walking endurance after training with a robotic device and conventional overground therapy.[35] However, two of the three trials included in the above review had both complete and incomplete SCI participants. In a recent meta-analysis involving people with acute incomplete SCI, a greater improvement in walking distance, mobility status, and functionality was observed after training with Lokomat as compared to overground training.[36]
The relation of walking speed to ambulatory status has been studied in SCI. It suggests that the individuals who walk with a minimum walking speed of >0.4 m/s and >0.7 m/s can walk with and without aids, respectively. A speed greater than 0.15 m/s enables individuals with SCI to walk indoors and use a wheelchair outdoors.[37] The mean walking velocity of participants in our pilot study in G2 was 0.69 m/s, and they could walk either independently or with a brace. After training with REARS, the mean walking speed of individuals in G1 was 0.2 m/s.
The minimum real difference that is clinically meaningful for 10MWT, 6MWT, and TUG is a change of 0.13 m/s, 45.8 m, and 10.8 s, respectively.[16] In the present study, we observed a change of 0.11 m/s, 42 m and 13.5 s for the above outcome measures (G2), respectively. A clinically significant change was observed in the TUG score, and the change in 10MWT and 6MWT approached the clinically meaningful difference.
A recent systematic review reported improvement in lower extremity motor scores, reduction in spasticity, and greater walking capacity after training with a robotic device. The trials included in this review had participants with both complete and incomplete SCI.[38]
Robotic gait training has an overall beneficial effect on the functional ability of SCI patients. A study that compared robotic gait training (Lokomat) combined with conventional therapy vis-a-vis overground training alone reported improvement in mobility (6 vs 3 point change in median score, combined vs overground, respectively, using SCIM score) and ambulation (median score 8 vs 5 point, combined vs overground, respectively, using WISCI score).[39] The mean total SCIM scores increased by 27 and 7 points after training with REARS in G1 and G2 groups, respectively, in our study. In a previous study done at our center, we observed a mean increase of 6.2 points in the WISCI II from admission to discharge in SCI (traumatic and non-traumatic) individuals undergoing conventional therapy.[4] However, in that study, we had included participants with motor complete status at admission (n = 37 out of 66), which might may have contributed to a lesser change in WISCI II as compared to the present study where we observed a 10-point increase (in G1) from baseline. In G2, which had individuals who could perform the 6MWT, WISCI II scores were high at baseline with not much scope for further change.
Adverse events like fracture in the tibia and calcaneus, ankle edema, and pressure ulcer at the point of contact with the device during training with the robotic exoskeleton have been reported.[10],[40],[41] In the present study, we observed no falls, pressure ulcer, or fracture during training; however, there were device malfunctions which were recorded and addressed by the engineering team.
Strengths and limitations
This was a pilot study with a small sample size; hence, the findings cannot be generalized to the SCI population regarding the beneficial effects of the device. A randomized, controlled study with larger sample size and longitudinal design would be able to determine the benefits and sustainability of gains out of this gait training. We observed that REARS is safe for gait training. As the device is been manufactured locally, we were able to overcome a lot of issues faced by the centers in the country, like huge cost of robotic devices imported from western countries, availability of the equipment locally, engineering support around the clock, etc.
Conclusions Robotic gait training with REARS is safe and feasible. Training with REARS may lead to an improvement in balance and walking capacity as observed in gait parameters, namely, walking distance and walking speed during the pilot phase. There is an improvement in independence, as assessed by SCIM, and reduction in the need for assistive devices, as assessed by WISCI.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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