The Orthotic Effect of Functional Electrical Stimulation on Reactive Stepping for People With Incomplete Spinal Cord Injury

Abstract

Background: Individuals with incomplete spinal cord injury (iSCI) often face challenges initiating reactive steps, leading to an increased risk of falls. Reactive balance training (RBT) can improve balance control; however, it is difficult to participate in RBT without the ability to initiate a reactive step independently. Functional electrical stimulation (FES) has been used to facilitate participation in RBT. FES applied to the common fibular nerve (CFN) following iSCI initiates a flexor withdrawal response, promoting rapid hip and knee flexion and ankle dorsiflexion, potentially aiding the execution of reactive stepping responses. This cross-sectional study aimed to evaluate the orthotic (i.e., immediate) effect of FES on reactive stepping parameters in participants with chronic, motor iSCI.

Methods: Sixteen individuals with chronic motor iSCI completed the Lean-and-Release test, which elicits reactive stepping through a simulated forward fall. Participants completed 10-20 trials, with FES applied in half at random. The behavioral response (i.e., single-step, two-step, ≥ 3-step, or fall) of each trial was recorded. Temporal parameters (i.e., foot-off time, swing time, and stepping time) and spatial parameters (i.e., length, height, and width) of the first reactive step were also recorded.

Results: The proportion of single-step (p = 0.31), two-step (p = 0.19), ≥ 3-step (p = 0.44) and fall (p = 0.42) behavioral responses did not differ between FES and No-FES conditions. Additionally, the temporal (foot-off time (p = 0.43), swing time (p = 0.80), and step time (p = 0.95)) and spatial parameters (length (p = 0.73), height (p = 0.70), and width (p = 0.54)) of the first reactive step did not differ between conditions.

Conclusions: FES had no orthotic effect on reactive stepping parameters in individuals with chronic motor iSCI.

Keywords: balance; falls; functional electrical stimulation; postural control; reactive stepping; spinal cord injury.