Article

Changes in impulse during the first rocker (braking force) and third
rocker (propulsion force) may affect changes in gait speed after orthotic
intervention. The purpose of this investigation was to objectively measure
changes in impulse during double support and correlate those findings to changes
in gait speed with and without ankle foot orthosis in individuals with
hemiplegia. METHODS: Fifteen adults with stroke-related hemiplegia walked with
and without ankle foot orthosis while foot pressure data was collected
bilaterally. Outcome measures included: gait cycle time (s), mean force (N), and
impulse (Ns) in the wholefoot, hindfoot, forefoot, and toe box during initial
double support and terminal double support. FINDINGS: Time significantly
decreased during the entire gait cycle, initial double support, and terminal
double support, with the ankle foot orthosis. During initial double support,
affected limb impulse significantly decreased with the ankle foot orthosis in the
wholefoot (P=0.016), and hindfoot (P=0.006), and hindfoot impulse % change and
gait speed % change were significantly correlated (P=0.007). During terminal
double support, affected limb impulse was not significantly different in the
wholefoot or forefoot and these changes were not significantly correlated to gait
speed. INTERPRETATION: Previous research found that orthotics increase gait speed
in individuals with hemiplegia. This research suggests that the increase in speed
is not due to increased propulsive forces at the end of terminal double support,
but due to decreased braking forces during initial double support. Therefore, the
orthosis preserved the first ankle rocker and provided a more efficient weight
acceptance which positively affected gait speed.
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