Preservation of the first rocker is related to increases in gait speed in individuals with hemiplegia and AFO.

BACKGROUND: 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.