Overground vs. treadmill-based robotic gait training to improve seated balance in people with motor-complete spinal cord injury: a case report

Abstract

Background: Robotic overground gait training devices, such as the Ekso, require users to actively participate in triggering steps through weight-shifting movements. It remains unknown how much the trunk muscles are activated during these movements, and if it is possible to transfer training effects to seated balance control. This study was conducted to compare the activity of postural control muscles of the trunk during overground (Ekso) vs. treadmill-based (Lokomat) robotic gait training, and evaluate changes in seated balance control in people with high-thoracic motor-complete spinal cord injury (SCI).

Methods: Three individuals with motor-complete SCI from C7-T4, assumed to have no voluntary motor function below the chest, underwent robotic gait training. The participants were randomly assigned to Ekso-Lokomat-Ekso or Lokomat-Ekso-Lokomat for 10 sessions within each intervention phase for a total of 30 sessions. We evaluated static and dynamic balance control through analysis of center of pressure (COP) movements after each intervention phase. Surface electromyography was used to compare activity of the abdominal and erector spinae muscles during Ekso and Lokomat walking.

Results: We observed improved postural stability after training with Ekso compared to Lokomat during static balance tasks, indicated by reduced COP root mean square distance and ellipse area. In addition, Ekso training increased total distance of COP movements during a dynamic balance task. The trunk muscles showed increased activation during Ekso overground walking compared to Lokomat walking.

Conclusions: Our findings suggest that the Ekso actively recruits trunk muscles through postural control mechanisms, which may lead to improved balance during sitting. Developing effective training strategies to reactivate the trunk muscles is important to facilitate independence during seated balance activity in people with SCI.

Keywords: Balance; Gait; Motor activity; Robotics; Spinal cord injury.

Fig. 1

A picture of the seated balance control measurement setup; a participant is seated on the forceplate with feet off the ground, and b the computer monitor displays the limits of stability test (COP position – green dot, baseline limit – red box, movement direction – yellow arrow)

Fig. 2

Gait speed is plotted for each training session per participant (P1 – solid black line, P2 – solid grey line, P3 – dotted black line). Gait speed was determined by the 10MWT for Ekso training, and the maximum speed achieved during Lokomat training

Fig. 3

COP outcome measures are plotted for baseline 1, baseline 2, and post each intervention phase; mean COP RDIST, RVEL and AREA-CE of the static balance tasks (a eyes open and b eyes closed), and c mean total distance of the dynamic balance task

Fig. 4

a the normalized muscle activity patterns of the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles are plotted over the gait cycle for P1 for all conditions; Ekso (EKSO –black line), and Lokomat (LOKO – grey line). The baseline activity (BAS – light grey shaded area) recorded during quiet lying is also displayed. b the average RMS amplitude across participants is plotted as a bar for each condition. Individual data from each participant is also displayed (P1 – circle, P2 – square, P3 – star)