Date of Award

12-2022

Degree Type

Thesis

Department

Biomechanics Research Building

First Advisor

Dr. Brian Knarr

Abstract

The purpose of this thesis was to investigate how different assistive devices impact the gait characteristics of stroke survivors. In two different sections, we investigated how an ankle foot-orthosis (AFO) impacts the gait and muscle activity of stroke survivors, and how the use of treadmill handrails impacts the stability margins of stroke survivors while walking on the treadmill. First, we used an articulated AFO device fabricated with an individual-specific design using a 3D scanner and a 3D printer to personalize the AFO foot plate and calf section, which we assembled with a triple action joint for each participant. The joints enabled independent tuning and testing of the impact of plantarflexion and dorsiflexion resistances on the participants and we tested a low, medium, and high resistance for each condition. Our findings showed that the AFO device systematically changed the muscle activity and the kinetics and kinematic gait characteristics of the participants. We noted significant phase changes for the plantarflexion resistances on the peak tibialis anterior and rectus femoris muscle activity in swing, the peak ankle dorsiflexion moment, knee flexion angle at the initial stance, and the ankle angle at initial stance. The dorsiflexion resistance significantly impacted the peak dorsiflexion angle and the peak positive ankle power of the participants.

In the second study, we used a visual biofeedback system to modulate the treadmill conditions of No hold, Light touch, and self-selected handrail use to examine how three treadmill handrail-use situations affect the stability margins of stroke survivors. When holding the handrails with a self-selected hold while walking on the treadmill, the participants' anteroposterior and mediolateral margins of stability for their paretic leg increased as compared to a light touch or no handrail use. The self-selected handrail use also impacted the participants' non-paretic leg, increasing its anteroposterior margin of stability and decreasing its mediolateral margin of stability.

These findings from both studies demonstrate that assistive devices can help improve the biomechanics and walking characteristics of stroke survivors, though additional research will provide a clearer guide on how to prevent unintended adaptations and potential complications from prolonged use.

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