Assessment of In-Hospital Walking Velocity and Level of Assistance in a Powered Exoskeleton in Persons with Spinal Cord Injury

Abstract

Background: Individuals with spinal cord injury (SCI) often use a wheelchair for mobility due to paralysis. Powered exoskeletal-assisted walking (EAW) provides a modality for walking overground with crutches. Little is known about the EAW velocities and level of assistance (LOA) needed for these devices.

Objective: The primary aim was to evaluate EAW velocity, number of sessions, and LOA and the relationships among them. The secondary aims were to report on safety and the qualitative analysis of gait and posture during EAW in a hospital setting.

Methods: Twelve individuals with SCI ≥ 1.5 years who were wheelchair users participated. They wore a powered exoskeleton (ReWalk; ReWalk Robotics, Inc., Marlborough, MA) with Lofstrand crutches to complete 10-meter (10 MWT) and 6-minute (6MWT) walk tests. LOA was defined as modified independence (MI), supervision (S), minimal assistance (Min), and moderate assistance (Mod). Best effort EAW velocity, LOA, and observational gait analysis were recorded.

Results: Seven of 12 participants ambulated ≥ 0.40 m/s. Five participants walked with MI, 3 with S, 3 with Min, and 1 with Mod. Significant inverse relationships were noted between LOA and EAW velocity for both 6 MWT (Z value = 2.63, Rho = 0.79, P = .0086) and 10 MWT (Z value = 2.62, Rho = 0.79, P = .0088). There were 13 episodes of mild skin abrasions. MI and S groups ambulated with 2-point alternating crutch pattern, whereas the Min and Mod groups favored 3-point crutch gait.

Conclusions: Seven of 12 individuals studied were able to ambulate at EAW velocities ≥ 0.40 m/s, which is a velocity that may be conducive to outdoor activity-related community ambulation. The ReWalk is a safe device for in-hospital ambulation.

Trial registration: ClinicalTrials.gov NCT02118194.

Keywords: ReWalk; community ambulation; gait analysis; gait velocity; level of assistance; paralysis; powered exoskeleton; spinal cord injury.

Figures

Figure 1.

Study flow diagram. Nineteen participants were consented for screening eligibility. Seven participants were screening failures: one for low bone mineral density (BMD), one for metal implant, one for unrelated medical condition, one for being over the weight limit, one did not complete screening, one had schedule conflict due to travel issues, and one was discharged due to poor attendance compliance. Twelve participants have data on the walking tests.

Figure 2.

Boxplots of level of assistance and exoskeletal-assisted walking (EAW) velocity results from 6-minute walk test (6MWT) (Z value = 2.63, Rho = 0.792, P = .0086) and 10-meter walk test (10MWT) (Z value = 2.62, Rho = 0.790 = 0.790, P = .0088) where Mod = moderate assistance (n = 1); Min = minimal assistance (n = 3); S = supervision (n = 3); and MI = modified independence (n = 5). The horizontal lines sequentially represent the 10th (at the bottom), 25th, 50th, 75th, and 90th (top line) percentiles.