Graduation Year


Document Type




Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Biomedical Engineering

Major Professor

Rajiv Dubey, Ph.D.

Co-Major Professor

Stephanie L. Carey, Ph.D.

Committee Member

Derrick Robertson, M.D.

Committee Member

Kyle Reed, Ph.D.

Committee Member

William Lee, Ph.D.


Ankle-foot-orthosis, Functional Electrical Stimulation, Gait Biomechanics, Ratings of Perceived Exertion, Walking Confidence


This dissertation explores how multimodal walking impacts quantitative and qualitative aspects of gait for persons with multiple sclerosis (pwMS) experiencing foot-drop. Foot-drop can dramatically impede mobility and clinicians routinely prescribe ankle-foot-orthosis (AFO) and functional electrical stimulation (FES) devices to alleviate its impacts on daily life. However, little is known about how these devices affect pwMS while traversing environments with real-world complexity. To explore this topic, an interventional, parallel assigned study was conducted. A realistic nature pathway containing changes in floor pitch, audiovisual stimulation, and during-trial tasks (for dual-tasking) was generated in an immersive virtual reality system called CAREN: Computer Assisted Rehabilitation ENvironment (Motek Medical, Netherlands). All participants wore a full-body set of 46 motion capture markers and had complete, passive control of their walking speeds. The primary outcome measures (OMs) of this study pertain to overall mobility and gait parameter symmetry. The secondary OMs are ratings of perceived exertion and confidence in walking ability. This study provides a normative cohort of thirteen participants aged 28 to 64 years; a case study of a pwMS, 58 years of age, who used two types of AFOs and an FES device; a cohort of three AFO-users aged 58 to 63 years, resulting in four AFO trials; a customized CAREN program that produces a realistic walking environment and collects full-body motion capture data; a detailed study protocol that can be modified for other populations, types of gait impediments, or types of interventions; anecdotal insights; and recommendations for future research.