Walking Ankle Robot for Foot Drop in Aging and Disabled Populations: A Demonstration Project

Study Overview
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Brief Summary
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The purpose of this research study is to test the utility of an ankle robot, when used during treadmill walking, in people with ankle weakness and foot drop from a peripheral nervous system injury due to neuromuscular or orthopedic injury.

Detailed Description
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Many individuals with central nervous system (CNS) injuries (e.g., a stroke) or peripheral nervous system (PNS) injuries (e.g., peroneal nerve injury, neuropathy, radiculopathy, and/or musculoskeletal injury) that affect their ankle movement have residual impairments that affect their walking and balance. These impairments include the disability foot drop, which increases the risk for falling. This study will focus on PNS injuries that cause foot drop. Current therapy to address foot drop is limited primarily to the use of ankle foot orthoses (braces) that help keep the foot from hitting the ground to prevent falling. Also, some individuals with foot drop use functional electrical stimulation to the leg nerve to lift the foot. Regardless, none of these, or other existing, methods to address foot drop cures or even improves significantly the underlying neurological deficit behind this disability. Braces improve walking safety only while they are worn, and functional electrical stimulation does not work when it is turned off, or when the nerve has been severely damaged. Thus, the increased fall risk due to foot drop is generally considered life-long and incurable. The investigators have developed a shoe-interfaced ankle robot with an adaptive control system, to assist an individual with ankle movement only as needed. Data from the investigators' previous studies on foot drop due to stroke show great promise for this ankle robot as a new rehabilitation tool for invididuals with foot drop, when used during treadmill walking. The investigators would like to utilize our findings from these stroke studies in learning how they can be used for PNS-related foot drop.

Official Title
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Walking Ankle Robot for Foot Drop in Aging and Disabled Populations: A Demonstration Project

Conditions
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Foot Drop, Peripheral Nervous System Diseases, Gait Disorders, Neurologic, Mobility Limitation

Intervention / Treatment
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* Device: Treadmill Ankle Robot Training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women, aged 18 to 88 years Chronic foot drop and ankle weakness in one leg from a peripheral nervous system injury due to a neuromuscular or orthopedic injury Ability to walk 10 meters and arise from a chair with no human assistance (but usage of usual assistive device[s] is permitted) Exclusion Criteria: Cardiac history of (a) unstable angina; (b) recent (less than 3 months) myocardial infarction, congestive heart failure (NYHA category II); and/or (c) hemodynamically significant valvular dysfunction Hypertension that is a contraindication for a bout of walking training (greater than 160/100 mmHg on two assessments) Medical history of (a) recent hospitalization (less than 3 months) for severe medical disease; (b) symptomatic peripheral arterial occlusive disease; (c) orthopedic or chronic pain conditions that significantly alter gait function; (d) pulmonary or renal failure; and/or (e) active cancer Current participation in orthopedic or rehabilitation medical programs Active deep venous thrombosis Distal paretic leg skin lesions, infections, or soft tissue inflammation

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 88 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Treadmill Ankle Robot Training<br> | Device: Treadmill Ankle Robot Training<br>* This intervention employs the use of an adaptive ankle robot control system, during treadmill walking, over a 6-week intervention period.<br>|

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 | cm/sec | Change from baseline to: post-6 weeks of training, and 6 weeks after completion of training | 
| Peak dorsiflexion angle during swing phase of gait | degrees; extent of ankle dorsiflexion to enable foot clearance | Change from baseline to: post-6 weeks of training, and 6 weeks after completion of training | 
| Ankle dorsiflexion-plantarflexion range of motion | degrees | Change from baseline to: post-6 weeks of training, and 6 weeks after completion of training | 
| Postural sway areas during quiet standing | cm^2; extent of postural deviations to assess static postural control | Change from baseline to: post-6 weeks of training, and 6 weeks after completion of training | 
| 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 weeks of training, and 6 weeks after completion of training | 
| Push-off forces during gait initiation | Newtons; magnitude of forward ground reaction forces. | Change from baseline to: post-6 weeks of training, and 6 weeks after completion of training |