DOI
https://doi.org/10.25772/8N3J-CG82
Defense Date
2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Biomedical Engineering
First Advisor
Dr. Paul Wetzel
Abstract
Upper extremity abnormal flexor synergy caused by stroke can impair individuals by coupling upper extremity muscles with deltoid activation. Previous studies have shown that reduction in deltoid loading can decrease flexor synergy. Robotic rehabilitation has the ability to allow for reduced deltoid loading while assisting or constraining joints along the arm to increase rehabilitation outcomes. The effects of higher degree of freedom low impedance robotics needs to be tested to learn how various parameters affect flexor synergy in comparison to end point robotics. During the first experiment, we tested 16 chronic stroke patients with flexor synergy problems in 3 tasks. Patients performed two synergy assessment tasks at different gravity compensation levels to measure their elbow extension and grip. The third task was a cup reaching tasks. Patients reached for a cup using different movement modes to either assist or constrain their joints. EMG and grip force levels were measured during these tasks. The results showed that increased gravity compensation and assistance lead to better functional outcomes while constraining the joints can be used to correct the trajectory of the arm. Electrophysiological outcomes showed promising results that gravity compensation was decoupling the flexor synergy, but further research is needed to concretely prove these changes. During the second experiment, 12 healthy controls performed a VR reaching task with 2 different gravity compensation levels and 3 dwell times. Subjects were instructed to use whichever arm they wished when a target appeared. The results showed increasing gravity compensation led to increased usage of the robotic device. Interestingly, the kinematics of the robotic device decreased compared to the nonrobotic device arm. This shows the importance for learning and training when using robotic devices especially for rehabilitation.
Rights
© Shawn DiRocco
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
7-31-2025