Combining neural stimulation and a powered exoskeletal knee to enhance walking after stroke.

In this study, we developed a unilateral, hybrid exoskeleton designed to augment post-stroke mobility through integration of noninvasive neural stimulation and a motorized knee orthosis. We evaluated proof of concept for this hybrid exoskeleton in a stroke survivor by assessing whether: (1) the motor and transmission possess sufficient backdrivability to facilitate effective muscle-generated movements, (2) the motor can independently drive movement, and (3) the combined application of stimulation and motor generate kinematic improvements superior to either modality used in isolation. The device was evaluated on an ambulatory stroke survivor under four overground walking conditions: (1) without the device, (2) stimulation only while wearing the exoskeleton, (3) motor assistance only, and (4) hybrid stimulated and motorized assistance. A motion capture system was used to obtain lower limb joint angles to assess the differences in each walking condition. Changes towards neurotypical hip, knee and ankle angles were found between the gait with no device compared to the assistive conditions. Hip-knee cyclograms suggest hybrid assistance most resembled neurotypical gait. Individually, neural stimulation and motor assistance resulted in improved gait kinematics and hybrid assistance provided greater improvement than each form of individual assistance.