Multicentric investigation on the safety, feasibility and usability of the ABLE lower-limb robotic exoskeleton for individuals with spinal cord injury: a framework towards the standardisation of clinical evaluations

Abstract

Background Robotic lower-limb exoskeletons have the potential to provide additional clinical benefits for persons with spinal cord injury (SCI). However, high variability between protocols does not allow the comparison of study results on safety and feasibility between different exoskeletons. We therefore incorporated key aspects from previous studies into our study protocol and accordingly conducted a multicentre study investigating the safety, feasibility and usability of the ABLE Exoskeleton in clinical settings. Methods In this prospective pretest-posttest quasi-experimental study across two SCI centres in Germany and Spain, in- and outpatients with SCI were recruited into a 12-session training and assessment protocol, utilising the ABLE Exoskeleton. A follow-up visit after 4 weeks was included to assess after-training outcomes. Safety outcomes (device-related adverse events (AEs), number of drop-outs), feasibility and usability measures (level of assistance, donning/doffing-time) were recorded at every session together with changes in gait parameters and function. Patient-reported outcome measures including the rate of perceived exertion (RPE) and the psychosocial impact of the device were performed. Satisfaction with the device was evaluated in both participants and therapists. Results All 24 participants (45 ± 12 years), with mainly subacute SCI (< 1 year after injury) from C5 to L3, (ASIA Impairment Scale A to D) completed the follow-up. In 242 training sessions, 8 device-related AEs (pain and skin lesions) were reported. Total time for don and doff was 6:50 ± 2:50 min. Improvements in level of assistance and gait parameters (time, steps, distance and speed, p < 0.05) were observed in all participants. Walking function and RPE improved in participants able to complete walking tests with (n = 9) and without (n = 6) the device at study start (p < 0.05). A positive psychosocial impact of the exoskeleton was reported and the satisfaction with the device was good, with best ratings in safety (participants), weight (therapists), durability and dimensions (both). Conclusions Our study results prove the feasibility of safe gait training with the ABLE Exoskeleton in hospital settings for persons with SCI, with improved clinical outcomes after training. Our study protocol allowed for consistent comparison of the results with other exoskeleton trials and can serve as a future framework towards the standardisation of early clinical evaluations. Trial Registrationhttps://trialsearch.who.int/, DRKS00023503, retrospectively registered on November 18, 2020.

Randomized, Crossover Clinical Trial on the Safety, Feasibility, and Usability of the ABLE Exoskeleton: A Comparative Study with Knee-Ankle-Foot Orthoses

“…Pain is another well-known potential risk when using robotic exoskeletons [3,6,22,24,34]. In this study, only one AE (out of five) was classified as device-related for the ABLE Exoskeleton and it was in the left hand of one of the participants.…”

“…Skin damage in areas that are in contact with the device is the most common risk of using wearable exoskeletons [6,24,50], even in those with FDA and CE approval:…”

“…Likewise, due to the lack of information provided in similar studies and the divergence in the clinical protocols and/or population, direct comparisons with other exoskeletons are difficult to be done [3,17,21,22]. The feasibility and usability of the ABLE Exoskeleton were also assessed in [24]. The latter study reported improvements of 290%, 300%, and 180% in the distance covered, the number of steps, and the gait speed, respectively; which are higher than the ones found in our work.…”

“…The safety and feasibility of wearable exoskeletons for gait rehabilitation after SCI have been evaluated in previous studies [3,[17][18][19][20][21][22][23][24]. In fact, a number of exoskeletons have already been certified for use in the clinical setting [6] or even at home [25,26].…”

“…Various studies tested the use of wearable exoskeletons in people with SCI to perform different tasks [34][35][36][37][38][39][40]. However, all the preceding studies assessed hip-knee-powered exoskeletons, and only one used a knee-powered exoskeleton [24]. The latter examined the use of the ABLE Exoskeleton in people with SCI, both with motor complete and incomplete injuries, and primarily in the acute or subacute phase (i.e., onset of paralysis injury within the last year).…”