Robot-Assisted Ankle Rehabilitation Using the Hybrid Assistive Limb for Children after Equinus Surgery: A Report of Two Cases

Abstract

After equinus corrective surgery, repetitive exercises for ankle dorsiflexion and plantar flexion are crucial during rehabilitation. The single-joint Hybrid Assistive Limb (HAL-SJ) is an advanced exoskeletal robotic device with a control system that uses bioelectrical signals to assist joint motion in real time and demonstrates joint torque assistance with the wearer’s voluntary movement. We present two cases of robot-assisted ankle rehabilitation after equinus surgery using the HAL-SJ in children. Case 1 was an 8-year-old boy, whereas case 2 was a 6-year-old boy. When they were allowed to walk without braces, training with the HAL-SJ was performed postoperatively for 20 min per session a total of eight times (2–4 sessions per week). Assessments were performed before and after HAL-SJ training. During gait analysis, case 1 had improved joint angles during the stance phase on the operated side; however, case 2 had improved joint angles during the stance and swing phases. The co-activation index values of the medial gastrocnemius and tibialis anterior muscles, which were high before training, decreased after training and approached the standard value. The HAL-SJ may provide systematic feedback regarding voluntary ankle dorsiflexion and plantar flexion and is considered to have motor learning effects.

Combined Ankle Robot Training and Robot-assisted Gait Training Improved the Gait Pattern of a Patient with Chronic Traumatic Brain Injury

“… 11 ) It is highly unlikely that use of the existing walking robot alone will improve motor paralysis of the ankle joint, but there are reports that use of the HAL® in the sitting position increases muscle strength and increases the dorsiflexion angle of the ankle joint during the free leg phase of walking after use in peroneal nerve palsy and childhood cerebral palsy. 14 , 15 ) The results of the present study are consistent with these reports. Based on the above, we believe that the combined use of two robots, a walking robot and an ankle robot, may have improved motor function in the knee and ankle, respectively.…”

“… 36 ) This may also be influenced by a reduction in ankle joint spasticity, and co-contraction has been reported to have decreased with the use of the HAL®. 15 ) However, no improvement in plantarflexion was obtained in the present study. Therefore, the floor reaction force data did not show any improvement in paretic propulsion, and no improvement in push-off was observed in terms of kinematics.…”

“…Past reports of the use of the medical single-joint HAL® in patients with peroneal nerve palsy and cerebral palsy have described increased muscle strength, increased gait speed, and improvement in the maximum dorsiflexion angle during the free leg phase. 14 , 15 ) In the present case, voluntary movements were triggered, the assistance level was adjusted to allow the patient to perform bottom and dorsiflexion movements in the full range of motion, and 500 repetitions of bottom and dorsiflexion movements in the sitting position with knee flexion at 90° were performed daily. Assistance was provided in the dorsiflexion direction (red arrow in Fig.…”

“…It has been shown to increase muscle strength and improve the dorsiflexion angle of the ankle joint during the swing phase of walking after use in patients with peroneal nerve palsy and pediatric cerebral palsy. 14 , 15 )…”

Use of Robot-Assisted Ankle Training in a Patient with an Incomplete Spinal Cord Injury: A Case Report

“…The single-joint-type HAL (HAL-SJ, Cyberdyne, Inc., Tsukuba, Japan) is a robot that can support flexion and extension movements of various joints. Previously, interventions for elbow and knee joint dysfunction have been reported [ 8 , 9 , 10 , 11 ], but with the expansion of the ankle joint unit, it is being explored for ankle joint dysfunction [ 12 ]. Furthermore, the use of HAL-SJ has been reported to improve the function of elbow joint muscles that failed to contract voluntarily in patients with cervical cord injury (C4 level) [ 13 ].…”