3-D Evaluation of Abnormal Upper Extremity Joint Coupling Post-Stroke

Area of Science:

• Neurorehabilitation
• Biomechanics
• Human Movement Science

Background:

• Stroke frequently causes abnormal upper extremity (UE) joint coupling, limiting independent joint control and functional arm use.
• Previous research primarily focused on in-plane joint coupling, neglecting out-of-plane movements crucial for coordinated motion across all UE degrees of freedom (DOFs).

Purpose of the Study:

• To develop and validate a 3D motion capture-based method for evaluating both in-plane and out-of-plane joint coupling across seven UE DOFs.
• To introduce a novel Joint Coupling Ratio (JCR) for quantifying these coupling patterns.
• To investigate the contribution of abnormal in- and out-of-plane joint coupling to functional deficits post-stroke.

Main Methods:

• Utilized 3D motion capture to assess joint coupling during isolated shoulder, elbow, and wrist movements and an object transfer task in 18 individuals post-stroke.
• Developed and applied a method to calculate the in- and out-of-plane Joint Coupling Ratio (JCR) for seven UE DOFs.
• Employed hierarchical regression analysis to determine the relationship between joint coupling abnormalities and functional task deficits.

Main Results:

• Abnormal in- and out-of-plane joint coupling was observed in the paretic arm of individuals post-stroke, indicated by significantly higher JCR values compared to the non-paretic arm.
• A regression model incorporating both in- and out-of-plane joint coupling explained a significant 33.8% of the variance in functional deficits, including movement duration, hand trajectory smoothness, trunk displacement, hand movement extent, and peak velocity time.
• Models using only in-plane or out-of-plane coupling explained less variance than the combined model.

Conclusions:

• The developed evaluation method advances the understanding of post-stroke abnormal joint coupling across all UE DOFs.
• Assessing both in- and out-of-plane joint coupling provides a more comprehensive understanding of stroke-induced impairments in independent UE joint control.
• These findings highlight the importance of considering multi-planar joint coupling for effective rehabilitation strategies aimed at improving functional arm use after stroke.