Enhancing Voluntary Motion in Broad Patient Populations With Modular Powered Orthoses

Study Overview
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Brief Summary
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The overall goal of this project is to develop modular, lower-limb, powered orthoses that fit to user-specific weakened joints and control force/torque in a manner that enhances voluntary motion in broad patient populations. This project aims to establish feasibility of assisting different populations with these modular powered orthoses. The investigators hypothesize that assisting lower-limb musculature with modular powered orthoses will improve 1) lifting/lowering posture in able-bodied subjects and 2) functional outcomes in elderly subjects.

Detailed Description
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The overall goal of this project is to develop modular, lower-limb, powered orthoses that fit to user-specific weakened joints and control force/torque in a manner that enhances voluntary motion in broad patient populations. Conventional orthoses tend to immobilize joints, and emerging powered orthoses constrain voluntary motion by using highly geared electric motors and/or control methods that force the user to follow a specific gait pattern. Consequently, these devices have not seen widespread success across populations with weakened voluntary control due to advanced age, musculoskeletal disorders, etc. These heterogeneous populations require partial, not full, assistance of user-specific muscle groups during daily activities. However, there is a fundamental gap in knowledge about how to design and control powered orthoses to assist the user without constraining their motion. The central hypothesis of this project is that high-torque, low-inertia motor systems controlled with energetic objectives will enable modular powered orthoses to partially assist the joints. High-torque electric motors combined with minimal transmissions can be freely rotated (i.e., backdriven) by human joints, allowing the use of an emerging torque control method called energy shaping to reduce the perceived weight/inertia of the body during any motion. By mounting these modular actuators to commercial orthoses, this technology will be easily prescribed/configured by clinicians. This project aims to establish feasibility of assisting different populations with modular powered orthoses. The investigators hypothesize that assisting lower-limb musculature with modular powered orthoses will improve 1) lifting/lowering posture in able-bodied subjects and 2) functional outcomes in elderly subjects.

Official Title
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Enhancing Voluntary Motion in Broad Patient Populations With Modular Powered Orthoses

Conditions
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Lower-limb Orthoses, Frailty/Sarcopenia, Chronic Overuse Musculoskeletal Injuries

Intervention / Treatment
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* Device: Modular powered orthosis


Participation Criteria
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Eligibility Criteria
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Inclusion criteria for able-bodied, young participants will be: Aged between 18 to 65 years Weigh less than 250 lbs due to limitations in the design of the orthoses Ability to lift and lower a 10 kg weight using the neutral-spine squat technique for 10 repetitions Exclusion criteria for able-bodied, young adult participants will be: Pregnant (self-report) Any significant neuromuscular or musculoskeletal disorder that would interfere with the study Prior history of chronic lower-back pain Unable to walk for 20 minutes History of any cardiovascular, vestibular, or visual diseases and/or impairments that may interfere with the study Cognitive deficits that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. Cognitive deficits will be determined by a Mini-Mental State Examination (MMSE) score of <22. Adults with a known allergy to medical grade tape Inclusion criteria for elderly participants will be: Aged between 65 to 85 years Weigh less than 250 lbs due to limitations in the design of the orthoses Ability to walk 6 minutes without assistance from a person (may use walking aid) Exclusion criteria for elderly participants will be: Pregnant (self-report) Significant pain due to arthritis or other joint problems that would limit their ability to walk Any recent lower-extremity fracture (within 3 months) Significant neurological (e.g., stroke), orthopedic, or cardiovascular disorder that may affect the ability to walk Advised by a physician not to walk or exercise Uncontrolled hypertension or diabetes Cognitive deficits or visual impairment that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. Cognitive deficits will be determined by a Mini-Mental State Examination (MMSE) score of <22. Adults with a known allergy to medical grade tape

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Exoskeleton<br>Participants in this arm of the study will perform various tasks while wearing the modular powered orthosis | Device: Modular powered orthosis<br>* This study will investigate modular, lower-limb, powered orthoses that fit to user-specific weakened joints and control force/torque in a manner that enhances voluntary motion in broad patient populations. The central hypothesis is that high-torque, low-inertia motor systems controlled with energetic objectives will enable modular powered orthoses to partially assist the joints. High-torque electric motors combined with minimal transmissions can be freely rotated (i.e., backdriven) by human joints, allowing the use of an emerging torque control method called energy shaping to reduce the perceived weight/inertia of the body during any motion. By mounting these modular actuators to commercial orthoses, this technology will be easily prescribed/configured by clinicians.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Powered orthosis effect | For each orthosis module tested, electromyography (EMG) readings will be normalized per-muscle by the peak EMG observed during the no-orthosis condition, and then averaged over the cycle and across repetitions to obtain normalized exertion values. Performance will be assessed by the difference in normalized exertion between the orthosis condition and no-orthosis condition, averaging across tasks and muscles measured for the joint module to compute the powered orthosis effect for each subject. | 1 day | 
| Time to complete 10 reps of lifting/lowering | Time to complete 10 reps of L&L will be measured post-fatigue in healthy subjects. | 1 day, assessed per experimental condition (i.e. with orthosis and without orthosis) | 
| User satisfaction | User satisfaction / perception of device effectiveness over an ambulation circuit (sit-to-stand, walk up and down a ramp, walk up and down a staircase) will be measured post-fatigue in healthy subjects using a modified QUEST survey. | 1 day, assessed per experimental condition (i.e. with orthosis and without orthosis) | 
| Gait speed | Gait speed will be determined by the time to complete a 10-meter walk test. This will be the primary outcome measure for elderly subjects. | 1 day, assessed per experimental condition (i.e. with orthosis and without orthosis) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Thorax angle | This is the global thorax angle (with respect to vertical) during a lifting/lowering cycle. This will be a secondary outcome measure for able-bodied subjects. | 1 day, assessed per experimental condition (i.e. with orthosis and without orthosis) |