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Mediolateral footpath stabilization during walking in people following stroke
Pei-Chun Kao1, Shraddha Srivastava2
1Department of Physical Therapy, University of Massachusetts Lowell, Lowell, Massachusetts, United States of America.
Plos One
|November 30, 2018
Summary
Stroke survivors exhibit altered coordination during walking, with excessive joint motion variability paradoxically reducing stability. This highlights a potential target for improving post-stroke gait and reducing fall risk.
Area of Science:
- Neuroscience
- Biomechanics
- Rehabilitation Science
Background:
- Falls are a major concern for community-dwelling stroke survivors, often occurring during walking.
- Understanding the control of mediolateral (side-to-side) foot placement during walking is crucial for identifying mechanisms of post-stroke gait instability.
Purpose of the Study:
- To investigate how stroke survivors coordinate lower-extremity joint movements to stabilize their mediolateral foot placement during walking.
- To determine the relationship between this inter-joint coordination and overall walking stability in post-stroke individuals.
Main Methods:
- Employed the Uncontrolled Manifold (UCM) approach to analyze kinematic data from nine stroke subjects and nine healthy controls walking on a treadmill at various speeds.
- UCM analysis differentiates motion variance into 'good variance' (consistent foot placement) and 'bad variance' (inconsistent foot placement).
Main Results:
- Both groups demonstrated significantly more 'good' than 'bad' variance, indicating active stabilization of foot placement.
- Stroke survivors showed stronger kinematic synergy for foot placement stabilization (greater relative variance difference) compared to controls.
- In healthy individuals, kinematic synergy was strongest in mid-swing and weakest in late swing; this phase-dependency was lost in late swing for stroke survivors.
- Contrary to healthy gait, stronger kinematic synergy in stroke survivors was associated with *less* walking stability.
Conclusions:
- Stroke survivors exhibit altered inter-joint coordination strategies for foot placement control during walking.
- While stroke survivors display enhanced kinematic synergy for foot placement, this does not translate to improved walking stability and may even be detrimental.
- Excessive 'good variance' in stroke gait, despite maintaining foot placement accuracy, may negatively impact overall walking stability, suggesting a need for novel rehabilitation approaches.
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