Post-stroke Stiff-Knee gait: are there different types or different severity levels?

Area of Science:

• Biomechanics
• Neurorehabilitation
• Gait Analysis

Background:

• Stiff-Knee gait (SKG), characterized by reduced knee flexion during swing, is common after stroke.
• The underlying causes and potential subtypes of SKG remain debated, impacting intervention effectiveness.

Purpose of the Study:

• To investigate potential subtypes of Stiff-Knee gait (SKG) in stroke survivors based on motor control complexity.
• To differentiate SKG based on kinematic and kinetic compensatory strategies during walking.

Main Methods:

• Retrospective analysis of kinematic, kinetic, and muscle activity data from 50 stroke survivors and 15 controls.
• Time-series kernel k-means cluster analysis applied to frontal plane kinematics to identify gait patterns.
• Non-negative matrix factorization used to assess underlying motor control differences.

Main Results:

• Three clusters (A, B, C) were identified based on compensatory frontal plane kinematics, gait speed, and propulsion asymmetry.
• Clusters A and B, characterized by hip hiking and varying degrees of knee flexion and gait speed, represented the majority of clinician-diagnosed SKG.
• No fundamental differences in underlying motor control were found between clusters despite kinematic and kinetic variations.

Conclusions:

• The identified clusters likely represent different severities of gait impairment in stroke survivors rather than distinct subtypes of Stiff-Knee gait.
• Gait speed and propulsion asymmetry appear to be key indicators differentiating these gait patterns.
• Further research is needed to refine understanding and optimize clinical interventions for SKG post-stroke.