Effect of Ankle-Foot Orthoses on the Sagittal Plane Displacement of the Center of Mass in Patients With Stroke Hemiplegia: A Pilot Study

Abstract

Background: Ankle-foot orthoses (AFOs) have been reported to have positive effects on the temporal-spatial parameters and kinematics and kinetics of gait in patients with stroke. The center of mass (COM) may be used to represent whole body movement and energy cost in gait, and therefore COM movement would also be positively influenced with use of an appropriate AFO. Objective: To investigate the effect of AFOs on the sagittal plane displacement of the COM in patients with stroke hemiplegia. Methods: Five male subjects with stroke hemiplegia participated in this pilot study. The trajectory of the COM in the sagittal plane, gait speed, bilateral step length, step width, and bilateral stance time were analyzed while participants ambulated under 2 test conditions: with an AFO or with footwear only. The height of the 2 peaks of the vertical displacement of the COM in a gait cycle was subsequently measured and normalized to body height. Statistical analyses were conducted using a nonparametric Friedman test. Results: Gait speed, bilateral step length, and the normalized peak height of the vertical COM trajectory during stance phase on the affected leg all revealed statistically significant increases (P < .05), and step width showed significant decreases (P < .05) under the AFO condition when compared to the footwear-only condition. Conclusions: An AFO may influence the vertical displacement of the COM in patients with stroke hemiplegia. The results of this pilot study therefore suggested that vertical movement of COM could potentially serve as a useful parameter to evaluate the effect of an AFO.