A Novel Mechanics-based Intervention to Improve Post-stroke Stability

Study Overview
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Brief Summary
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The purpose of this study is to determine whether a novel treadmill training intervention can improve the gait stabilization strategy used by individuals who have experienced a stroke.

Detailed Description
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Every year, approximately 15,000 American Veterans experience a stroke, with an estimated cost of acute and follow-up care in the hundreds of millions of dollars. Following a stroke, the restoration or improvement of walking is a high-ranking goal among patients, but only about half of the population is able to return to typical levels of community ambulation. The resultant decrease in independent mobility is strongly associated with a decline in quality of life. Gait instability is a common contributor to limited mobility through either an increased fall-risk or fear of falling, but current interventions to address post-stroke gait instability have had limited success. This project will conduct initial testing of a novel elastic force-field designed to improve post-stroke gait stability through targeted motor learning. The results of these experiments will serve as the basis for the development of novel gait rehabilitation techniques, which have the potential to increase the quality of life of thousands of Veterans and save millions of dollars.

Official Title
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A Novel Mechanics-based Intervention to Improve Post-stroke Gait Stability

Conditions
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Stroke

Intervention / Treatment
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* Behavioral: Error reduction
* Behavioral: Error augmentation
* Behavioral: Activity matched control


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: At least 21 years old Experience of a stroke 6 months prior to participation Preferred overground gait speed of at least 0.2 m/s Ability to walk at self-selected speed for 3 minutes without a cane or walker Provision of informed consent. Exclusion Criteria: Resting heart rate above 110 beats/min Resting blood pressure higher than 200/110 mm Hg History of congestive heart failure, unstable cardiac arrhythmias, hypertrophic cardiomyopathy, severe aortic stenosis, angina or dyspnea at rest or during activities of daily living Preexisting neurological disorders or dementia History of major head trauma Legal blindness or severe visual impairment Life expectancy <1 yr; 8) History of deep vein thrombosis or pulmonary embolism within 6 months Uncontrolled diabetes with recent weight loss, diabetic coma, or frequent insulin reactions Orthopedic injuries or conditions (e.g. joint replacements) in the lower extremities with the potential to alter the gait pattern.

Ages Eligible for Study
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Minimum Age: 21 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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Error reduction<br>Participants will complete a 12-week training program, in which they practice walking on a treadmill for 30-minutes during twice-weekly training sessions. During these sessions, participants will interface with a custom-built force-field able to exert mediolateral forces on the legs, which will be in error reduction mode. This training period will be followed by a 12-week follow-up period. Five assessment sessions will be interspersed throughout this total 24-week period. | Behavioral: Error reduction<br>* During training sessions, a custom-built force-field will exert forces on the legs while participants walk. These forces will push the legs toward mechanically-appropriate mediolateral locations, having the effect of reducing the errors in foot placement that are often present among individuals who have experienced a stroke.<br>|
| Experimental: Error augmentation<br>Participants will complete a 12-week training program, in which they practice walking on a treadmill for 30-minutes during twice-weekly training sessions. During these sessions, participants will interface with a custom-built force-field able to exert mediolateral forces on the legs, which will be in error augmentation mode. This training period will be followed by a 12-week follow-up period. Five assessment sessions will be interspersed throughout this total 24-week period. | Behavioral: Error augmentation<br>* During training sessions, a custom-built force-field will exert forces on the legs while participants walk. These forces will push the legs away from mechanically-appropriate mediolateral locations, having the effect of amplifying the errors in foot placement that are often present among individuals who have experienced a stroke.<br>|
| Sham Comparator: Activity matched control<br>Participants will complete a 12-week training program, in which they practice walking on a treadmill for 30-minutes during twice-weekly training sessions. During these sessions, participants will interface with a custom-built force-field able to exert mediolateral forces on the legs, which will be in transparent mode. This training period will be followed by a 12-week follow-up period. Five assessment sessions will be interspersed throughout this total 24-week period. | Behavioral: Activity matched control<br>* During training sessions, participants will interface with a custom-built force-field while they walk. The force-field will essentially get out of the way, producing minimal forces on the legs, and having no direct effect on the errors in foot placement that are often present among individuals who have experienced a stroke.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Partial Correlation Between Pelvis Displacement and Paretic Step Width During Gait (Change From Baseline) | A custom measure that quantifies the strength of the relationship between body mechanics and foot placement. This measure falls within a relatively narrow range among neurologically intact controls, but is substantially reduced in some individuals who have experienced a stroke, indicating a reduced ability to stabilize their gait pattern. This measure relates the mechanical state of the body at the start of each step (mediolateral pelvis displacement and velocity of the pelvis relative to the stance foot) to the step width at the end of the step. Specifically, the partial linear correlation between pelvis displacement and step width was calculated, accounting for variation in pelvis velocity. The change in this measure relative to baseline is calculated at four time points (after 4, 8, 12, and 24 weeks). | baseline, 4-weeks, 8-weeks, 12-weeks, 24-weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Functional Gait Assessment (Change From Baseline) | A commonly-used clinical test to quantify balance and stability during various walking tasks. The minimum value is 0, the maximum value is 30, and higher scores indicate better outcomes. The total maximum value of 30 is calculated as the sum of 10 subscores, each of which has a scoring range of 0-3 and represents a distinct walking task. The change in this measure relative to baseline is calculated at four time points (after 4, 8, 12, and 24 weeks). | baseline, 4-weeks, 8-weeks, 12-weeks, 24-weeks | 
| Activities-specific Balance Confidence Scale (Change From Baseline) | A commonly-used clinical scale that quantifies an individual's confidence in performing various tasks requiring balance. The minimum value is 0, the maximum value is 100, and higher scores indicate a better outcome. The overall score is calculated as the mean of 16 subscores, each of which can range of 0 to 100 and represents self-efficacy at a distinct movement task. The change in this measure relative to baseline is calculated at four time points (after 4, 8, 12, and 24 weeks). | baseline, 4-weeks, 8-weeks, 12-weeks, 24-weeks | 
| 10-meter Walk Test (Change From Baseline) | A commonly-used clinical test to quantify general gait function. Walking speed is measured during the middle 6-meter portion of a 10-meter straight line path. The change in this measure relative to baseline is calculated at four time points (after 4, 8, 12, and 24 weeks). | baseline, 4-weeks, 8-weeks, 12-weeks, 24-weeks | 
| Fall Incidence | Self-report history of fall occurrence, quantified by the average number of falls per participant in each group during the 12-week period that followed completion of the study's intervention component | 6 months (during 12 week follow-up period) | 
| Fear of Falling | Self-report statement of whether a participant has a fear of falling | 6 months (at completion of 12-week Follow-up period) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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stroke, rehabilitation, gait