Clinical utility of the over-ground bodyweight-supporting walking system Andago in children and youths with gait impairments

Abstract

Background: The Andago is a rehabilitation robot that allows training walking over-ground while providing bodyweight unloading (BWU). We investigated the practicability, acceptability, and appropriateness of the device in children with gait impairments undergoing neurorehabilitation. Concerning appropriateness, we investigated whether (i) stride-to-stride variability of the stride time and inter-joint coordination was higher when walking over-ground in Andago versus treadmill walking, and (ii) activation of antigravity leg muscles decreased with higher levels of BWU.

Methods: Eighteen children and adolescents with gait impairments participated in three sessions. Practicability was assessed by determining the time needed to get a patient in and out of Andago, the accuracy of the BWU system, and other aspects. Acceptability was assessed by patients responding to questions, while six therapists filled out the System Usability Scale. To determine appropriateness, the participants were equipped with surface electromyography (sEMG) electrodes, electrogoniometers and accelerometers. Various parameters were compared between walking over-ground and on a treadmill, and between walking with three different levels of BWU (median: 20%, 35% and 50% of the bodyweight) over-ground.

Results: Practicability: the average time needed to get in and out of Andago amounted to 60 s and 16 s, respectively. The BWU system seemed accurate, especially at higher levels. We experienced no technical difficulties and Andago prevented 12 falls. However, participants had difficulties walking through a door without bumping into it. Acceptability: after the second session, nine participants felt safer walking in Andago compared to normal walking, 15 preferred walking in Andago compared to treadmill walking, and all wanted to train again with Andago. Therapists rated the usability of the Andago as excellent. Appropriateness: stride-to-stride variability of stride duration and inter-joint coordination was higher in Andago compared to treadmill walking. sEMG activity was not largely influenced by the levels of BWU investigated in this study, except for a reduced M. Gluteus Medius activity at the highest level of BWU tested.

Conclusions: The Andago is a practical and well-accepted device to train walking over-ground with BWU in children and adolescents with gait impairments safely. The system allows individual stride-to-stride variability of temporospatial gait parameters without affecting antigravity muscle activity strongly.

Trial registration: ClinicalTrials.gov Identifier: NCT03787199.

Keywords: Bodyweight unloading; Cerebral palsy; Feasibility; Over-ground bodyweight support; Pediatric neurorehabilitation; Practicability; Rehabilitation technology; Stride-to-stride variability.

Conflict of interest statement

Dr. van Hedel chairs a network, the Advanced Robotic Therapy Integrated Centers (ARTIC). The network receives financial and personal support from the company Hocoma, who is also the company commercializing the Andago. The company had no influence on any part of this work. The authors report no further competing interests.

Figures

Fig. 1

Andago and custom-made pressure detection system. a Andago with its various components. b Photo, and c schematic drawing of handrail equipped with custom-made pressure force detection system. The middle band of each sensor was covered with a stripe (‘force guiding layer’) to increase the thickness of the sensor in the recording area. Sensors and stripes were covered with tape (to improve robustness), and a tube was inserted around the bar to decouple support and grasping forces. BWU bodyweight unloading

Fig. 2

Study procedures. Schematic drawing showing the study procedures. At appointment 1, patient characteristics and functional measures were assessed. Participants were able to practice walking with Andago and on the treadmill. Finally, some questions were asked. At appointment 2, we evaluated the accuracy of the bodyweight unloading system, allowed practicing, and again asked participants about their acceptability of Andago. At appointment 3, participants performed first the 10 MWT at maximal speed twice. Then, EMG electrodes, accelerometers, and goniometers were mounted, after which the measurements in Andago and on the treadmill were performed at the reference bodyweight unloading level (BWUref). This was followed by walking in Andago with the two other BWU levels. Finally, the 10MWT at maximal speed was repeated twice again. MMT manual muscle testing, SCALE selective control assessment of the lower extremity, 10MWTss 10-m walk test at self-selected speed, 10MWT max 10-m walk test at maximal speed, BWU bodyweight unloading, FMS functional mobility scale, GFAQ Gillette functional assessment questionnaire walking scale

Fig. 3

Practicability aspects of the Andago. a Average time [s] with standard deviation required to get patients in and out of Andago. b–d Comparison of the bodyweight unloading (BWU) as set in Andago compared to the actual values for conditions of 25%, 50%, and 75% of BWU, respectively. BWU, bodyweight unloading

Fig. 4

Acceptability of Andago by participants and therapists. Pie-charts showing the number of participants who a felt safer walking in Andago compared to normal walking, b preferred to train with Andago compared to treadmill walking, and c would like to train again with Andago. d Individual patient responses, whether it was cool training in Andago. Results from session 1 are colored in blue, from session 2 in red. e Individual System Usability Scale (SUS) scores for six therapists (Th1-6). Average and standard deviation (SD) are visualized with red crossing lines; the percentile score (displayed by the red up/down arrow) was calculated and interpreted in line with Bangor et al. [29]. SD standard deviation, Th therapist

Fig. 5

Individual example. Adolescent participant walking a in the Andago and b on the treadmill. Stride-to-stride variability of the stride time between a and b is shown in (c; red for the Andago, orange for the treadmill). Variability over 30 strides in hip-knee inter-joint coordination (d and f) and (e) muscle activity of the M. Gluteus Medius. The participant and his parents provided (written) consent for publication

Fig. 6

Appropriateness of Andago. a Participants walked with higher stride-to-stride variability in stride time in Andago when compared to on the treadmill. b Also, the variability in inter-joint coordination between the hip and knee and the knee and ankle were higher when walking in Andago compared to the treadmill. c Antigravity leg muscle activity during the stance phase. CV coefficient of variation, RMS root mean square, EMG electromyography, M. Musculus, Ref reference bodyweight unloading (BWU); Ref + 15% or Ref + 30%, reference BWU plus additional 15% or 30%, respectively