Between-limb difference in peak knee flexion angle can identify persons post-stroke with Stiff-Knee gait.

Area of Science:

• Biomechanics
• Neurology
• Rehabilitation Medicine

Background:

• Stiff-Knee gait impacts 25-75% of post-stroke individuals, characterized by limited knee flexion during the swing phase.
• Inconsistent diagnostic measures, including peak knee flexion angle and timing, hinder reliable identification of Stiff-Knee gait.

Purpose of the Study:

• To evaluate the consistency, validity, and accuracy of different Stiff-Knee gait definitions in post-stroke individuals.
• To establish reliable diagnostic criteria for Stiff-Knee gait in stroke survivors.

Main Methods:

• Univariate cluster analysis was applied to 50 post-stroke participants (24 with and 26 without Stiff-Knee gait).
• Spearman's rank correlation and five clustering techniques assessed definition validity.
• Clinician evaluations were incorporated for validity analysis.

Main Results:

• Peak knee flexion timing and hyperextension showed poor correlation with reduced swing-phase knee flexion.
• The between-limb difference in peak swing knee flexion angle and angle at self-selected speeds were the most valid differentiators.
• At faster speeds, the between-limb difference demonstrated high sensitivity and F1 scores.

Conclusions:

• Thresholds of <44.3° peak swing knee flexion and >17.0° between-limb difference identify Stiff-Knee gait at self-selected speeds.
• The between-limb difference in peak swing knee flexion angle is recommended for diagnosing post-stroke Stiff-Knee gait due to its gait speed robustness.