Evaluating Wearable Robotic Assistance on Gait

Evaluating Wearable Robotic Assistance on Gait Mechanics and Energetics in Individuals With Neurological Impairment

The overarching goal of this study is to improve mobility in individuals with movement disorders through advances in wearable assistance (i.e. powered orthoses).

Design (Aim 1): To test the hypothesis for Aim 1, we will systematically adjust the magnitude of powered ankle assistance as ambulatory individuals with CP walk on over-ground walking at self-selected speeds, on a treadmill at set speeds, and on stair-stepping machine at a constant rate. The bi-directional ankle device will provide dorsi-flexion assistance if the participant has foot-drop. We will compare powered assistance to each participant's baseline walking condition (shod or AFOs); we will recruit a cohort where half of the participants walk with prescribed AFOs. We will measure three-dimensional motion capture, electromyography, and metabolic respiration data, and assess subject perception of exertion and benefit during the walking and stair trials for each level of assistance. Data collection will take place following a practice visit. Design (Aim 2): To test the hypotheses for Aim 2, the same individuals with gait deficits from CP from Aim 1 will be randomly selected to complete 30 minutes of over-ground gait training with individually-tuned plantar-flexor assistance 4x/week for 1 week or 2x/week for 2 weeks. The magnitude of assistance during training will be set at the amount that maximized metabolic cost of transport during level walking in Aim 1 for each participant and kept constant.

Metabolic energy required to walk will be measured using a portable metabolic measurement system (Cosmed K5). Units: J/kg/m

A motion capture system will be used to measure the posture of the body during walking. Units: Degrees

A motion capture system and force plates will be used to measure the forces produced by the muscles of the body during walking. Units: Nm

Inclusion Criteria: Age between 5 and 35 years old, inclusive. Either a healthy volunteer or a diagnosis of a neurologically-based walking disorder due to stroke, spinal cord injury, Parkinson's disease, or cerebral palsy. Must be able to understand and follow simple directions based on parent report and clinical observation during the history and physical examination. Able to provide verbal assent, if appropriate. If the participant is non-verbal, parental interpretation of gesticulation for assent will be used. The ability to read and understand English. Able to walk at least 30 feet with or without a walking aid (GMFCS Level I-III for individuals with cerebral palsy) Exclusion Criteria: • Any neurological, musculoskeletal or cardiorespiratory injury, health condition ( including pregnancy), or diagnosis other than stroke, spinal cord injury, Parkinson's disease or cerebral palsy that would affect the ability to walk as directed for short periods of time.

Orekhov G, Fang Y, Cuddeback CF, Lerner ZF. Usability and performance validation of an ultra-lightweight and versatile untethered robotic ankle exoskeleton. J Neuroeng Rehabil. 2021 Nov 10;18(1):163. doi: 10.1186/s12984-021-00954-9.