The relationship between gait asymmetry and stability in people with sub-acute stroke

BackgroundPeople with stroke often walk with temporal asymmetry; which is related to increased fall risk. The purpose of this study was to determine the relationship between temporal gait asymmetry and mechanical stability among people with sub-acute stroke. MethodsThirty-one people with sub-acute stroke (<6 months post-stroke) completed six walking trials in a biomechanics laboratory. Three-dimensional motion capture was recorded. Swing symmetry was calculated as a ratio of swing time on the more affected limb divided by swing time on the less affected limb. Mechanical stability was the minimum margin of stability, relative to the medial and lateral borders of the stance limb, during the single support phase of the gait cycle. Multiple linear regression was used to determine the relationship between swing symmetry and mechanical stability, controlling for step width and walking speed. ResultsThere was a significant negative relationship between swing symmetry and lateral margin of stability on the less affected side (p<0.0001) and medial margin of stability on the more affected side (p=0.023). That is, as swing symmetry increased, the extrapolated centre of mass tended to be closer to the lateral border of the less affected side and farther from the medial border of the more affected side. ConclusionGait asymmetry could, in part, result from a strategy to compensate for poor balance control on the more affected side. Alternatively, reduced lateral margin of stability on the less affected side among asymmetric participants indicates instability in this direction and could increase the risk for falling.