Ankle Robot to Reduce Foot Drop in Stroke

Study Overview
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Brief Summary
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Deficits in ankle control after stroke can lead to foot drop, resulting in inefficient, aberrant gait and an elevated falls risk. Using a novel ankle robot and newly invented adaptive control system, this study tests whether robotic-assisted treadmill training will improve gait and balance functions in chronic stroke survivors with foot drop impairment. It is hypothesized that, compared to treadmill training alone, integrating adaptive ankle robotics with treadmill training will reduce drop foot during independent overground walking, resulting in greater mobility, improved postural control, and reduced fall risk.

Detailed Description
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This proposal investigates a novel ankle robot (anklebot) adaptive control approach integrated with treadmill training to reduce foot drop and improve mobility function in chronic hemiparetic stroke survivors. Currently, stroke survivors with foot drop are trained to live with a cane or other assistive device, and often ankle foot orthotics (AFOs) for safety. Neither mediates task-practice or neuromotor recovery. The investigators have developed an adaptive anklebot controller that detects gait cycle sub-events for precise timing of graded robotics assistance to enable deficit severity-adjusted ankle motor learning in the context of walking. The investigators' pilot findings show that 6 weeks treadmill training with anklebot (TMR) timed to assist swing phase dorsiflexion only is more effective than treadmill alone (TM) to improve free-walking swing dorsiflexion at foot strike, floor-walking speed, and the benefits are retained at 6 weeks post-training. Notably, swing-phase TMR training improved paretic leg push-off, and reduced center-of-pressure sway on standing balance, indicating potential benefits to other elements of gait and balance, beyond those robotically targeted toward foot drop. This randomized study investigates the hypothesis that 6 weeks TMR is more effective to improve durably gait biomechanics, static, and dynamic balance, and mobility function in chronic stroke survivors with dorsiflexion deficits, compared to TM alone. Aims are to determine the compare effectiveness of 6 weeks TMR vs. TM alone on: Independent gait function indexed by gait velocity, swing-phase DF (dorsiflexion), terminal stance push-off. Balance function indexed by measures of postural sway (CoP), asymmetric loading in quiet standing, peak paretic A-P forces in non-paretic gait initiation, and standardized scales for balance and fall risk. Long-term mobility outcomes, assessed by repeated measures of all key gait and balance outcomes at 6 weeks and 3 months after formal training cessation.

Official Title
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Adaptive Ankle Robot Control System to Reduce Foot-drop in Chronic Stroke

Conditions
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Stroke, Foot Drop

Intervention / Treatment
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* Device: Treadmill plus anklebot
* Behavioral: Treadmill only


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ischemic or hemorrhagic stroke > 2 months prior in men or women Residual hemiparesis of the lower extremity that includes symptoms of foot drop Capable of ambulating on a treadmill with handrail support Already completed all conventional physical therapy Adequate language and cognitive function to provide informed consent and participate in testing and training Exclusion Criteria: Cardiac history of: Unstable angina Recent (< 3 months) myocardial infarction Congestive heart failure (NYHA category II or higher) Hemodynamic valvular dysfunction Hypertension that is a contraindication for a bout of treadmill training (>160/100 mmHg on two assessments) Medical history of: Recent hospitalization (< 3 months) for any serious condition leading to significant bed-rest or reduction in mobility function Symptomatic peripheral arterial occlusive disease Orthopedic or chronic pain conditions restricting exercise Pulmonary failure requiring oxygen Uncompensated renal failure Active cancer Neurological history and exam consistent with: Dementia Receptive or global aphasia that confounds testing and training, operationally defined as unable to follow 2-point commands Non-stroke neurological disorder restricting exercise (e.g. Parkinson's Syndrome, myopathy) Untreated major depression

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Treadmill+anklebot<br>This group will receive gait training on a treadmill while wearing the anklebot with the adaptive control system. | Device: Treadmill plus anklebot<br>* This intervention employs the use of the adaptive anklebot control system to complement treadmill exercise training over a 6-week intervention period.<br>* Other names: TMR;|
| Active Comparator: Treadmill only<br>This group will receive gait training on a treadmill, without use of the anklebot. | Behavioral: Treadmill only<br>* This intervention employs the use of a treadmill for gait exercise training over a 6-week intervention period<br>* Other names: TM;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gait Velocity During Self-selected Overground Walking | Gait velocity during self-selected overground walking measured in cm/sec | Change from baseline to: Post 6-week training, 6 weeks after completion, and 3 (or 6) months after completion | 
| Anterior-posterior Propulsion Forces of Paretic Side During Gait | Newtons: anterior-posterior force generated during push-off phase of the gait cycle | Change from baseline to: Post 6-weeks training, 6 weeks after completion, and 3 (or 6) months | 
| Peak Dorsiflexion Angle During Swing Phase of Gait | Degrees; extent of ankle dorsiflexion to enable foot clearance | Change from baseline to: Post 6-week training, 6 weeks after completion, and 3 (or 6) months after completion | 
| Postural Sway Areas During Quiet Standing | cm^2; extent of postural deviations to assess static postural control | Change from baseline to: Post 6-week training, 6 weeks after completion, and 3 (or 6) months | 
| Ratio of Asymmetric Loading in Quiet Standing | Ratio of Newtons of force per each leg (paretic/nonparetic) while standing quietly | Change from baseline to: Post 6-week training, 6 weeks after completion, and 3 (or 6) months | 
| Peak Paretic Push Off Forces During Gait Initiation | Newtons; magnitude of forward ground reaction forces | Change from baseline to: Post 6-week training, 6 weeks after completion, and 3 (or 6) months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Rehabilitation, Robotics, Gait