Development of a New Ankle Joint Hybrid Assistive Limb

Foot and ankle disabilities (foot drop) due to common peroneal nerve palsy and stroke negatively affect patients' ambulation and activities of daily living. We developed a novel robotics ankle hybrid assistive limb (HAL) for patients with foot drop due to common peroneal nerve palsy or stroke. The ankle HAL is a wearable exoskeleton-type robot that is used to train plantar and dorsiflexion and for voluntary assistive training of the ankle joint of patients with palsy using an actuator, which is placed on the lateral side of the ankle joint and detects bioelectrical signals from the tibialis anterior (TA) and gastrocnemius muscles. Voluntary ankle dorsiflexion training using the new ankle HAL was implemented in a patient with foot drop due to peroneal nerve palsy after lumbar surgery. The time required for ankle HAL training (from wearing to the end of training) was approximately 30 min per session. The muscle activities of the TA on the right were lower than those on the left before and after ankle HAL training. The electromyographic wave of muscle activities of the TA on the right was slightly clearer than that before ankle HAL training in the resting position immediately after ankle dorsiflexion. Voluntary ankle dorsiflexion training using the novel robotics ankle HAL was safe and had no adverse effect in a patient with foot drop due to peroneal nerve palsy.

Automated summary

Foot and ankle disabilities, such as foot drop, caused by peroneal nerve palsy and stroke can greatly hinder patients' mobility and daily activities. In this study, we developed a novel robotics ankle hybrid assistive limb (HAL) to help patients with foot drop improve ankle movement. The ankle HAL is a wearable exoskeleton-type robot that trains the ankle joint through plantar and dorsiflexion exercises, using an actuator to detect bioelectrical signals from the muscles. Our experiment with a patient with peroneal nerve palsy after lumbar surgery showed that voluntary ankle dorsiflexion training with the ankle HAL was safe and had positive effects on muscle activity.