Biofeedback Controlled Ankle Foot Orthosis for Stroke Rehabilitation to Improve Gait Symmetry

Stroke affects 700,000 Americans per year resulting in the largest cause of long-term disability in the United States. Dropfoot is a common condition associated with residual disabilities of stokes and is characterized as a paralysis or weakness of the dorsiflexor muscles of the foot and ankle. The result is an abnormal gait cycle caused by the dragging of the foot and toes during the swing phase. This device attempts to incorporate key principles from Electromyography (EMG) biofeedback rehabilitation and active Ankle-Foot Orthosis (AFO) design into a single rehabilitation device. The goal is to achieve an improvement in gait symmetry between the affected and unaffected legs of stoke patients exhibiting drop-foot by providing an assisted dorsiflexion response triggered by the users own EMG signal during the swing phase. The design incorporates a modified walking brace utilizing a custom built ball-screw actuator driven by a DC motor. Surface electrodes placed over the tibialis anterior muscle of the user will record and analyze the EMG data in real-time. An EMG triggering threshold will be calibrated to each user’s ability to serve as a closed-loop control pathway for initiating the dorsiflexion response. Automatic motion capture gait analysis can be used to record markers placed on the participants lower limbs. A comparative review of the kinematics of both legs will be analyzed for symmetry during the patient’s normal gait cycle and the assisted gait cycle using the biofeedback AFO.