Characterizing Intersection Variability of Butterfly Diagram in Post-stroke Gait Using Kernel Density Estimation
Gait & Posture
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ackground:Center of pressure (COP) trajectory during treadmill walking have been commonly presented usingthe butterfly diagram to describe gait characteristics in neurologically intact and impaired individuals. However,due to the large amount of displayed information, the butterfly diagram is not an efficient solution to visualizelocomotor variability.Purpose:The purpose of this study was to evaluate post-stroke locomotor variability by applying Kernel densityestimation (KDE) on the intersections of the butterfly diagram, and to compare KDE derived metrics withconventional metrics of gait symmetry and variability.Methods:Bilateral toe-off(TO) and initial contact (IC) points of the butterfly diagram were determined to cal-culate the COP symmetry index and the intersections of bilateral TOeIC. Subsequently, the intersections duringthe walking window were used to evaluate its density and variability by Kernel density estimation. Standarddeviations of step width and step length were compared between groups.Results:Using the KDE surface plots we observed 4 characteristically different patterns with individuals post-stroke, which were associated with functional status quantified using walking speed and lower extremity Fugl-Meyer scores. However, locomotor variability quantified using standard deviations of step width and lengths didnot differ between groups.Significance & Novelty: This paper presents a novel approach of using KDE analysis as a better and moresensitive method to characterize locomotor COP variability in individuals with post-stroke hemiparesis, com-pared to conventional metrics of gait symmetry and variability.
Butterfly diagram; Center of pressure; Gait; Kernel Density Estimation; Locomotor variability
Rehabilitation and Therapy
Characterizing Intersection Variability of Butterfly Diagram in Post-stroke Gait Using Kernel Density Estimation.
Gait & Posture, 76