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

STUDY DESIGN: Cross sectional. OBJECTIVES: 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. SETTING: A tertiary SCI/D rehabilitation center in Canada. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Spatial characteristics of reactive stepping among people living with chronic incomplete spinal cord injury.

Objective: Compare the spatial characteristics of reactive stepping between individuals with chronic motor incomplete spinal cord injuries (iSCI) and able-bodied (AB) individuals.Design: Cross sectional.Setting: Lyndhurst Centre.Participants: Twelve individuals with iSCI (3 males, 53.6 ± 15.2 years old) and 11 age- and sex-matched AB individuals (3 males, 54.8 ± 14.0 years old).Interventions: The Lean-and-Release test was used to elicit reactive stepping. A horizontal cable, attached at waist height, was released when 8-12% body weight was supported in a forward lean position. Participants underwent up to 10 Lean-and-Release trials in a session. Kinematic and kinetic data were recorded.Outcome measures: The length, width and height of the first reactive step of each trial were calculated. Standard deviation between trials was calculated to represent the variability in step length, width and height within a participant. Among participants with iSCI, correlation coefficients were used to explore the relationship between step length and width variability and (1) Lean-and-Release test behavioral responses, (2) 3-month fall history, and (3) lower extremity strength.Results: Step length (P = 0.94), width (P = 0.52) and height (P = 0.97), normalized for participant height, did not differ between groups. Participants with iSCI showed greater variability in step length (P = 0.02) and width (P = 0.01), but not height (P = 0.32). No correlation was found between step length or width variability and behavioral responses, 3-month fall history, or lower extremity strength.Conclusions: Individuals with iSCI showed increased variability in length and width of reactive stepping compared to AB individuals, which may contribute to their impaired ability to execute single-step reactive responses.Trial registration: ClinicalTrials.gov identifier: NCT02960178.

Quantifying balance control after spinal cord injury: Reliability and validity of the mini-BESTest.

Context/Objective: Incomplete spinal cord injury (iSCI) causes deficits in balance control. The Mini-Balance Evaluation Systems Test (mini-BESTest) is a comprehensive measure; however, further testing of its psychometric properties among the iSCI population is needed. We evaluated the mini-BESTest's test-retest reliability, and concurrent and convergent validity among individuals living with iSCI for more than one year. Design: Cross-sectional study. Setting: Rehabilitation hospital. Participants: Twenty-one individuals with chronic motor iSCI (14 females, mean age 56.8 ± 14.0 years). Interventions: None. Outcome Measures: Participants completed the mini-BESTest at two sessions spaced two weeks apart. At the second session, participants performed tests of lower extremity muscle strength and quiet standing on a force platform with eyes opened (EO) and eyes closed (EC). Intraclass correlation coefficients (ICC) evaluated test-retest reliability. To evaluate concurrent and convergent validity, Pearson's correlation coefficient (r) quantified relationships between mini-BESTest scores and measures of center of pressure (COP) velocity during EO and EC standing, and lower extremity muscle strength, respectively. Results: Test-retest reliability of the mini-BESTest total score and sub-scale scores were high (ICC = 0.94-0.98). Mini-BESTest scores were inversely correlated with COP velocity when standing with EO (r = 0.54-0.71, P < 0.05), but not with EC. Lower extremity strength correlated strongly with mini-BESTest total scores (r = 0.73, P < 0.001). Conclusion: The mini-BESTest has high test-retest reliability, and concurrent and convergent validity in individuals with chronic iSCI.