Stimulation Combined With Powered Motorized Orthoses for Walking After Stroke

Objective: The goal of this study is to implement and test a neuro-mechanical gait assist (NMGA) device to correct walking characterized by muscle weakness, incoordination or excessive tone in Veterans with hemiparesis after stroke that adversely affects their ability to walk, exercise, perform activities of daily living, and participate fully in personal, professional and social roles. Research Plan: A prototype NMGA device will be used to develop a finite state controller (FSC) to coordinate each user's volitional effort with surface muscle stimulation and motorized knee assistance as needed. Brace mounted sensors will be used to develop a gait event detector (GED) which will serve the FSC to advance through the phases of gait or stair climbing. In addition, a rule-base intent detection algorithm will be developed using brace mounted sensors and user interface input to select among various functions including walking, stairs climbing, sit-to-stand and stand-to-sit maneuvers. The FSC controller tuning and intent algorithm development and evaluation will be on pilot subjects with difficulty walking after stroke. Outcome measures during development will provide specifications for a new prototype NMGA design which will be evaluated on pilot subjects to test the hypothesis that the NMGA improves walking speed, distance and energy consumption of walking. These baseline data and device will be used to design a follow-up clinical trial to measure orthotic impact of NMGA on mobility in activities of daily living at home and community. Methodology: After meeting inclusion criteria, pilot subjects will undergo baseline gait evaluation with EMG activities of knee flexors and extensors, ankle plantar and dorsiflexors and isokinetic knee strength and passive resistance. They will be fitted with a NMGA combining a knee-ankle-foot-orthosis with a motorized knee joint and surface neuromuscular stimulation of plantar- and dorsi- flexors, vasti and rectus femoris. Brace mounted se