Reactive stepping after a forward fall in people living with incomplete spinal cord injury or disease

Abstract

Cross sectional. To compare the reactive stepping ability of individuals living with incomplete spinal cord injury or disease (SCI/D) to that of sex- and age-matched able-bodied adults. A tertiary SCI/D rehabilitation center in Canada. Thirty-three individuals (20 with incomplete SCI/D) participated. Participants assumed a forward lean position in standing whilst 8-12% of their body weight was supported by a horizontal cable at waist height affixed to a rigid structure. The cable was released unexpectedly, simulating a forward fall and eliciting one or more reactive steps. Behavioral responses (i.e., single step versus non-single step) were compared using a Chi-square test. The following temporal parameters of reactive stepping were compared using t-tests: the onset of muscle activation in 12 lower extremity muscles (six per limb) and step-off, step contact and swing time of the stepping leg. Behavioral responses were significantly different between groups (χ2 = 13.9 and p < 0.01) with participants with incomplete SCI/D showing more non-single step responses (i.e., multi-steps and falls). The onsets of muscle activation were more variable in participants with incomplete SCI/D, but only the stepping tibialis anterior showed a significantly slower onset in this group compared with able-bodied adults (t = -2.11 and p = 0.049). Movement timing of the stepping leg (i.e., step-off, step contact, and swing time) was not significantly different between groups. Reactive stepping ability of individuals with incomplete SCI/D is impaired; however, this impairment is not explained by temporal parameters. The findings suggest that reactive stepping should be targeted in the rehabilitation of ambulatory individuals with SCI/D.