Clinical studies with the Indego
The lndego Personal is a lower extremity exoskeleton providing power assisted trunk stability in combination with dynamic flexion/extension of the knees and hips for standing, walking and returning to sit. This powered orthosis is beneficial for a broad range of neurological conditions.
In this article we look at how various studies have showcased the Indego’s performance.
Indego therapy in action
Ease of Learning and Usability
In a pilot clinical trial, 16 spinal cord injury (SCI) subjects completed five 1.5 hour training sessions with the lndego powered exoskeleton. At the end of five sessions all subjects were able to walk on indoor and outdoor surfaces. Distances covered in 6 minutes averaged 64 meters for those with CS-6, 74 meters for Tl-8, and 121 meters for T9-Ll. Average walking speed was 0.22 m/s for persons with CS-6 motor complete tetraplegia, 0.26 m/s for Tl-8 motor complete paraplegia, and 0.45 m/s for T9-Ll paraplegia. (5)
Results from this pilot study suggest that in just 7.5 hours of training, subjects with lower paraplegia, upper paraplegia and tetraplegia quickly learn how to ambulate on a variety of surfaces with the lndego system. Based on the average walking speeds recorded, results further suggest that some participants may be able to become limited community ambulators.
Mobility Assessment
In a prospective, multicenter, open-label clinical trial which involved 40 subjects across five sites, the following endpoints were observed in respect to general skills, walking speeds, levels of assistance, exertion and safety. (6)
General skills
97.5% (39/40) of subjects were able to complete a Timed Up-and-Go (TUG) test with minimal contact assistance required. One subject completed the TUG test with moderate assistance.
Walking Speed
Walking speed was captured by a 6 meter walking test (6MWT) and a 10 meter walking test (lOMWT). The average walking speed on indoor surfaces across all subjects reached 0.38 ± 0.08 m/s at the end of the study, with minimal contact assistance required, on average. The fastest walking speed achieved by any single subject in this study was 0.59 m/s. No significant difference in walking speed was seen between indoor or outdoor surfaces.
Additionally, other studies (7) have also demonstrated increased walking speeds by spinal cord injured patients, at lower physiological cost (as measured by the Physiological Cost Index or PCI), utilising actively powered orthotic systems vs traditional mechanical reciprocating gait orthosis (RGOs) and hip knee ankle foot orthoses (HKAFOs).
Levels of Assistance
Walking Index for Spinal Cord Injury (WISC-11) and Functional Independence Measure (FIM) scores were used to access participant's levels of assistance. WISC-11 and FIM scores were recorded at midpoint and final sessions then averaged. By midpoint in the sessions, the average participant required the use of a walker and one support person. By the end of the sessions, the average participant required the use of crutches and one support person. The level of assistance needed to complete the activities decreased as the sessions progressed.
Results across 10 additional studies have demonstrated that 76% percent of patients were able to ambulate with little to no physical assistance following exoskeleton training programs
Exertion
Participants completed questionnaires including a Borg Rating of Perceived Exertion which captured how much effort the participant felt they had to exert to walk on the indoor and outdoor surfaces. The average rating among participants for indoor ground level walking was 10 which corresponds to "light exercise" and "very light exercise".
Safety
There were no unanticipated or serious adverse events. Of the 1237 total study sessions, 44 adverse events were reported. 19 of the adverse events were device related and consisted of minor bruising, redness, abrasion and swelling. There was one instance of a rolled ankle. The overall cause of these adverse events was determined to be related to improper fitting and padding.
In the Miller et al. (8) meta analysis, the only 3 falls during exoskeleton training programs were seen across the 10 included studies.
According to the researchers:
"All three reported falls occurred in a single study while tethered and none resulted in injury. Falls were due to programming errors using a first-generation Ekso exoskeleton in two participants and due to malfunctioning of specialised forearm crutches that had been discontinued in one participant."
Since the lndego exoskeleton's commercial release in the United States and Europe, over 150 devices have been deployed to rehabilitation centres and personal use customers. No serious adverse events resulting in patient injury or falls have been reported by customers.
Bowel & Bladder Function
In a recently published study (9) of 45 subjects using the lndego exoskeleton, 20% of subjects reported a positive change in bowel management after only using the device for three hours per week over the course of 8 weeks. These patients cited fewer instances of neurogenic bowel dysfunction, less incontinence and constipation, and decreased time and assistance required for bowel management.
In one of the most comprehensive systematic reviews to date, researchers assessed available peer reviewed literature for FDA-approved powered lower limb exoskeletons, including the lndego. A meta analysis of publications identified three prospective case studies reporting bowel function outcomes. Across these studies, 61% (10) of patients experienced improved bowel movement regularity with exoskeleton use.
Spasticity
26% of participants have reported decreased spasticity from pre to post trial using lndego for 3 times per week for 8 weeks (7). Across five separate prospective studies (8) evaluating spasticity, 38% of patients have reported decreased spasticity with powered exoskeleton use.
Cardiovascular & Cardiopulmonary Health
Persons with SCI may have difficulty in engaging in regular physical activity to the level needed to maintain or improve cardiovascular health and fitness. A prospective case study (11) utilising lndego with spinal cord injured patients found exoskeleton assisted walking provided a moderate intensity activity (utilising Metabolic equivalent of tasks or METs scale) and increased cardiovascular response consistent with recommended guidelines for light to moderate exercise.
Similar results were found in a separate case study published by the Veterans Administration (12), where the participants demonstrated that routine use of a powered exoskeleton resulted in increased activity energy expenditure, consistent with light to moderate exercise, which would be expected to have positive cardiopulmonary and metabolic benefits for sci patients over long term use.
Pain
Several case studies have found reduction in chronic or neuropathic pain in sci subjects following exoskeleton use and training (13•14•15). And a more recent study (16) has found that exoskeleton use and training does not provoke or introduce new pain sensations in sci patients.
Bone Mineral Density
A 2017 study supports exoskeleton's value for improving musculoskeletal profiles in SCI patients. Using dual energy X-ray absorptiometry (DEXA), a gold standard for measuring body composition, investigators noted that adult patients significantly increased their lean leg and appendicular mass, reduced fat mass, and demonstrated increased calf muscle diameter following exoskeleton use. Patients' tibia bone mineral density also increased 14.5% (17) , a clinically significant change indicative of potential bone health improvement.
References
1) https://www.accessdata.fda.gov/cdrh_docs/pdfl7/K171334.pdf
2) Mayo Clinic - Spinal Cord Injury: Symptoms
3) Post & van Leeuwen (2012), Spinal Cord
4) Simpson et al. (2012) J Neurotrauma
5) Hartigan et al. (2015) Mobility Outcomes Following Five Training Sessions with a Powered Exoskeleton. Topics in Spinal Cord Injury. Spring;(21):93-9.
6) Farris et al. (2015) lndego Exoskeleton; Assessing Mobility for Persons with Spinal Cord Injury (SCI)
7) Arazpour ets al. (2013) The physiological cost index of walking with mechanical and powered gait orthosis in patients with spinal cord injury. Spinal Cord. May; 51(5):356-9
8) LE Miller et al. (2016) Clinical effectiveness and safety of powered exoskeleton-assisted walking in patients with spinal cord injury: systematic review with meta-analysis. Medical Devices: Evidence and Research, 9:455-466.
9) BS Juszczak et al. (2018) Examining the Effects of a Powered Exoskeleton on Quality of Life and Secondary Impairments in People Living with Spinal Cord Injury. Topics in Spinal Cord Injury Rehabilitation. August 2018. http ://archive.scijournal.com/ doi/10.1310/sci 17-00055
11) N Evans, et al (2015) Acute Cardiorespiratory and Metabolic Responses During Exoskeleton-Assisted Walking Overground Among Persons with Chronic Spinal Cord Injury. Topics in spinal cord injury rehabilitation, 21(2), 122- 32.
12) P Asselin et al (2015) Heart rate and oxygen demand of powered exoskeleton-assisted walking in persons with paraplegia. Journal of Rehabilitation Research & Development. 52(2) 147-158.
13) J Kressler et al. (2104) Understanding therapeutic benefits of overground bionic ambulation: exploratory case series in persons with chronic, complete spinal cord injury. Arch Phys Med Rehabil 2014; 95: 1878-1887.
14) SA Kolakowsky-Hayner et al. (2013) Safety and Feasibility of using the Ekso™ Bionic Exoskeleton to Aid Ambulation after Spinal Cord Injury. J Spine 2013; 54:003.
15) O Cruciger et al. (2016) Impact of locomotion training with a neurologic controlled hybrid assistive limb (HAL) exoskeleton on neuropathic pain and health related quality of life (HRQoL) in chronic SCI: a case study. Disabil Rehabil Assist Technol 2016; 11: 529-534.
16) C Bach et al. (2018) EXOSKELETON GAIT TRAINING AFTER SPINAL CORD INJURY: AN EXPLORATORY STUDY ON SECONDARY HEALTH CONDITIONS. Journal of Rehabilitation Medicine, 50: 806-813.
17) A Karelis et al. (2017) Effect on body composition and bone mineral density of walking with a robotic exoskeleton in adults with chronic spinal cord injury. Journal of Rehabilitation Medicine, 49: 84-87.