Ankle Robotics for Error Augmentation After Stroke

NCT07804342 | Enrolling By Invitation DMC FDA Device

• 1 other identifier: HP-00108406
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 2

Brief Summary

The goal of this pilot clinical trial is to test whether training with a portable ankle robot improves ankle push-off and walking speed in adults with chronic stroke who have ankle weakness. The study will also evaluate whether the device is safe and practical to use during walking rehabilitation. The main questions it aims to answer are: Does training with the portable ankle robot improve paretic ankle propulsion during walking? Does training with the portable ankle robot improve walking speed at self-selected and fast walking speeds? Participants will: Complete 30 training sessions of treadmill and overground walking while wearing the portable ankle robot, 3 to 4 times per week over 8 to 9 weeks Complete walking and movement assessments before training, after 15 sessions, and after 30 sessions Walk at self-selected and fast speeds while researchers measure ankle propulsion, gait symmetry, and walking speed

Conditions

Chronic Stroke

Keywords

error augmentation; robotics; device; walking

Outcome Measures

Primary Outcomes (1)

• Peak ankle plantarflexion propulsive torque during walking

  Peak ankle plantarflexion propulsive torque will be measured using force plates during overground walking to quantify propulsion generated by the paretic limb during the push-off phase of gait.

  Baseline (prior to intervention), 5 weeks after intervention initiation (following approximately 15 sessions), and 10 weeks after intervention initiation (following approximately 30 sessions)

Secondary Outcomes (3)

• Self-selected walking speed

  Baseline (prior to intervention), 5 weeks after intervention initiation (following approximately 15 training sessions), and 10 weeks after intervention initiation (following approximately 30 training sessions)

• Fast walking speed

  Baseline (prior to intervention), 5 weeks after intervention initiation (following approximately 15 training sessions), and 10 weeks after intervention initiation (following approximately 30 training sessions)

• Step Length Symmetry Ratio During Overground Walking Measured by Instrumented Walkway

  Baseline (prior to intervention), 5 weeks after intervention initiation (following approximately 15 training sessions), and 10 weeks after intervention initiation (following approximately 30 training sessions)

Study Arms (1)

AMBLE Robotic Gait Training

EXPERIMENTAL

Participants with chronic stroke will receive a 30-session gait training program using the AMBLE portable robotic ankle exoskeleton. Training will include treadmill and overground walking with individualized robotic resistance to improve ankle plantarflexion during push-off. Robotic assistance will be adjusted throughout the intervention based on participant performance and tolerance to promote active motor recovery and improve walking function.

Device: AMBLE

Interventions

AMBLE DEVICE

The AMBLE is a portable robotic ankle exoskeleton designed to provide individualized assistance and/or resistance during gait training. The device uses adaptive impedance-based control and real-time gait detection to provide dorsiflexion assistance during swing and plantarflexion assistance or resistance during push-off based on participant performance. It is used during treadmill and overground walking to promote recovery of ankle motor control and walking function.

AMBLE Robotic Gait Training

Eligibility Criteria

• Age: 18 Years - 88 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Chronic stroke, more than 6 months post-stroke
• Clinical evidence of hemiparetic gait
• Ankle dorsiflexion and plantarflexion strength on the affected side graded 1/5 (trace contraction) to 4/5 (reduced strength) on manual muscle testing
• Able to independently complete the 10-Meter Walk Test at a walking speed less than 1.0 m/s, with or without an assistive device

You may not qualify if:

• Self-reported unstable angina, myocardial infarction within the past 3 months, congestive heart failure (NYHA Class II), or hemodynamically significant valvular disease
• Self-reported hypertension that is a contraindication to routine physical therapy (greater than 160/100 mmHg on two assessments)
• Self-reported hospitalization within the past 3 months for severe medical illness
• Self-reported symptomatic peripheral arterial occlusive disease
• Self-reported orthopedic conditions or chronic pain that significantly alter gait function
• Self-reported pulmonary or renal failure
• Self-reported active cancer
• Self-reported history of a non-stroke neuromuscular disorder restricting gait
• Aphasia or cognitive functioning that confounds participation, defined as unable to follow two-step commands or by judgment of the evaluating therapist
• Self-reported history of cerebellar stroke or observable cerebellar signs
• Self-reported botulinum toxin prescribed for the lower extremities within the previous 3 months

Sponsors & Collaborators

• University of Maryland, Baltimore: lead
• NextStep Robotics Inc.: collaborator

Study Sites (2)

Allied Health Research Building

Baltimore, Maryland, 21042, United States

Location

Allied Health Research Building

Baltimore, Maryland, 21201, United States

Location

Related Publications (5)

• Forrester LW, Roy A, Krebs HI, Macko RF. Ankle training with a robotic device improves hemiparetic gait after a stroke. Neurorehabil Neural Repair. 2011 May;25(4):369-77. doi: 10.1177/1545968310388291. Epub 2010 Nov 29.

  PMID: 21115945 BACKGROUND

• Forrester LW, Roy A, Krywonis A, Kehs G, Krebs HI, Macko RF. Modular ankle robotics training in early subacute stroke: a randomized controlled pilot study. Neurorehabil Neural Repair. 2014 Sep;28(7):678-87. doi: 10.1177/1545968314521004. Epub 2014 Feb 10.

  PMID: 24515923 BACKGROUND

• Macko RF, Ivey FM, Forrester LW, Hanley D, Sorkin JD, Katzel LI, Silver KH, Goldberg AP. Treadmill exercise rehabilitation improves ambulatory function and cardiovascular fitness in patients with chronic stroke: a randomized, controlled trial. Stroke. 2005 Oct;36(10):2206-11. doi: 10.1161/01.STR.0000181076.91805.89. Epub 2005 Sep 8.

  PMID: 16151035 BACKGROUND

• Macko RF, Ivey FM, Forrester LW. Task-oriented aerobic exercise in chronic hemiparetic stroke: training protocols and treatment effects. Top Stroke Rehabil. 2005 Winter;12(1):45-57. doi: 10.1310/PJQN-KAN9-TTVY-HYQH.

  PMID: 15736000 BACKGROUND

• Westlake KP, Dudek K, Roy A, Henderson CE, Hornby TG. The Concept of Shaping Applied to Locomotor Interventions: Clinical and Robotic Strategies to Facilitate and Progress Variable Stepping Training at Higher Intensities. Neurorehabil Neural Repair. 2026 Jun 15:15459683261454948. doi: 10.1177/15459683261454948. Online ahead of print.

  PMID: 42290198 RESULT

Study Officials

• Kelly Westlake, PhD, PT

  University of Maryland, Baltimore

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Model Details: All enrolled participants will be assigned to a single intervention arm and receive the AMBLE robotic gait training intervention. Outcomes will be evaluated longitudinally using repeated assessments performed before, during, and after completion of the 30-session training program

Study Record Dates

• First Submitted: August 17, 2026
• First Posted: September 4, 2026
• Study Start: June 16, 2025
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: September 4, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (2)