Randomized controlled trial of robot-assisted gait training with dorsiflexion assistance on chronic stroke patients wearing ankle-foot-orthosis

Abstract

BackgroundRobot-assisted ankle-foot-orthosis (AFO) can provide immediate powered ankle assistance in post-stroke gait training. Our research team has developed a novel lightweight portable robot-assisted AFO which is capable of detecting walking intentions using sensor feedback of wearer’s gait pattern. This study aims to investigate the therapeutic effects of robot-assisted gait training with ankle dorsiflexion assistance.MethodsThis was a double-blinded randomized controlled trial. Nineteen chronic stroke patients with motor impairment at ankle participated in 20-session robot-assisted gait training for about five weeks, with 30-min over-ground walking and stair ambulation practices. Robot-assisted AFO either provided active powered ankle assistance during swing phase in Robotic Group (n = 9), or torque impedance at ankle joint as passive AFO in Sham Group (n = 10). Functional assessments were performed before and after the 20-session gait training with 3-month Follow-up. Primary outcome measure was gait independency assessed by Functional Ambulatory Category (FAC). Secondary outcome measures were clinical scores including Fugl-Meyer Assessment (FMA), Modified Ashworth Scale (MAS), Berg Balance Scale (BBS), Timed 10-Meter Walk Test (10MWT), Six-minute Walk Test (SMWT), supplemented by gait analysis. All outcome measures were performed in unassisted gait after patients had taken off the robot-assisted AFO. Repeated-measures analysis of covariance was conducted to test the group differences referenced to clinical scores before training.ResultsAfter 20-session robot-assisted gait training with ankle dorsiflexion assistance, the active ankle assistance in Robotic Group induced changes in gait pattern with improved gait independency (all patients FAC ≥ 5 post-training and 3-month follow-up), motor recovery, walking speed, and greater confidence in affected side loading response (vertical ground reaction force + 1.49 N/kg, peak braking force + 0.24 N/kg) with heel strike instead of flat foot touch-down at initial contact (foot tilting + 1.91°). Sham Group reported reduction in affected leg range of motion (ankle dorsiflexion − 2.36° and knee flexion − 8.48°) during swing.ConclusionsRobot-assisted gait training with ankle dorsiflexion assistance could improve gait independency and help stroke patients developing confidence in weight acceptance, but future development of robot-assisted AFO should consider more lightweight and custom-fit design.Trial registrationClinicalTrials.gov NCT02471248. Registered 15 June 2015 retrospectively registered.Electronic supplementary materialThe online version of this article (10.1186/s12984-018-0394-7) contains supplementary material, which is available to authorized users.

Effects of Wearable Ankle Robotics for Stair and Over-ground Training on Sub-acute Stroke: A Randomized Controlled Trial

“…An exoskeleton ankle robot has been developed and evaluated by our research team in a pilot randomized controlled trial (RCT) for chronic stroke subjects with foot drop problem. Our ndings showed chronic stroke subjects had signi cant improvement in gait independency and enhanced gait con dence at heel strike after 20-session gait training wearing this robot for stair and over-ground gait training [18]. Similar ankle rehabilitation robotics have also shown their potential to be an alternative gait rehabilitation for stroke [19][20][21][22][23], examples are Anklebot [8] and ReStore (ReWalk Robotics, USA) [24].…”

“…The robot weighted 0.5 kg (including AFO and motor) on the leg, with the control box (0.5 kg) held by the trainer. This robot had been evaluated in previous RCT which demonstrated greater functional improvement on chronic stroke [18]. The current RCT focused on evaluating its therapeutic effects on sub-acute stroke.…”

Systematic Review on Wearable Lower-Limb Exoskeletons for Gait Training in Neuromuscular Impairments

“…In contrast to studies with patients with SCI, studies with post-stroke patients assessed the gait performance, without wearing exoskeleton, after training with the exoskeleton and compared the results with the baseline measurements. In general, we found that the degree of mobility improvement was not as substantial as with the studies focusing on SCI patients: 12 out of 16 studies analyzing gait speed reported an improvement [37,47,87,102,[105][106][107][108][109][110][111][112], and only 3 out of 9 studies analyzing Flugl-Meyer scores reported an improvement [102,109,112]. Regarding the group of studies focusing on other pathologies, 4 out of 7 studies analyzing outcome measures related to gait speed reported an improvement [36,86,113,114].…”

A Review on the Control of the Mechanical Properties of Ankle Foot Orthosis for Gait Assistance

“…A bending stiffness control was implemented on a flexible rigid AFO. The AFO was able to bend to a certain degree as such AFOs are made from a thermal plastic material such as polypropylene [18,57], and carbon fiber [19]. The works reported AFOs with different bending stiffness values such as 0.19 N·m [23] and 2.52 N·m [58].…”

“…Then, on the third week, the user gait without the assistance of the AFO was analyzed. The effects of the provision of an AFO on rehabilitation was measured on an AFO with a bending stiffness control [57] in the short-term, long-term, and even in terms of the immediate effect (during the provision of the AFO) [16,19]. The immediate effects of an AFO with gait control, such as damping stiffness, assistive torque, and motion control, on the user have been reported, such as a higher walking speed, longer stride length, and so on [72], but without focusing on the short-term or long-term utilization [74,96].…”