Assessing the DSR Ankle

Study Overview
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Brief Summary
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This research is being done to conduct a preliminary investigation into a new prosthetic microprocessor controlled (MPC) ankle, called the Damping, Stiffness, and Repositioning (DSR) ankle. The DSR ankle is a new design to support a person while they walk on both even and uneven ground, as well as with bending the ankle for safe foot clearance while a person takes a step. In particular, in this study we are interested in seeing how this type of new device may benefit people who are rated as a K2-level ambulator.

Detailed Description
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Synchro Motion, LLC developed a novel MPC ankle. Because of its unique actuation scheme, the prosthesis can behave as: (1) a lockable conformal damper, (2) a variable set-point spring, and (3) an actively repositionable joint. The investigators therefore refer to the device as the damping, stiffness, and repositioning (DSR) ankle. The DSR ankle is small, lightweight, quiet, and runs for multiple days on a single charge. No other commercially available prosthesis combines this set of features. It will be shown in preliminary work that the features of the DSR ankle can increase toe clearance in swing, reduce the time-to-foot-flat after heel strike, and improve weight bearing symmetry when standing on slopes for K3 Individuals with Lower Limb Amputation (ILLAs). These biomechanical functions have all been linked to improved safety and stability, which leads the investigators to hypothesize that the DSR ankle may provide benefits to K2 ILLAs as well. The main purpose of this research is to determine the ways in which the DSR ankle may be adapted to provide benefits specifically to ILLAs who use their prosthesis at the K2 level. For purposes of the Phase I work, the development and assessment will be performed exclusively with K2 ILLAs in order to provide an opportunity to implement any necessary refinements to the DSR ankle to ensure optimal K2 performance. The remainder of the research is to quantify the effectiveness of the DSR ankle as compared to a predicate non-MPC ankle in improving performance for K2 ILLAs.

Official Title
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Assessment of a Microprocessor Ankle for Low Mobility Individuals

Conditions
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Amputation, Limb Deficiencies

Intervention / Treatment
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* Device: DSR Ankle
* Device: Predicate Ankle


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults aged 18-89 years Patients who have a unilateral transtibial amputation who are able to use a prosthesis and who currently use a passive, non-MPC prosthesis K2 level ambulators Exclusion Criteria: Pregnant women Children (<18 years old) Prisoners or institutionalized individuals Individuals who have the inability to give informed consent Participants unable to walk for 2 minutes without an assistive device Participants with complicating health conditions that interfere with the study Inability to read and understand the English language. As this is a pilot study with a small sample size, it is prohibitive to translate Study documents to other languages as recruitment will be from a sample of convenience.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 89 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: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: AB/BA
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: DSR Ankle<br>The DSR Ankle is a novel microprocessor-controlled ankle prosthesis that is able to provide enhanced mobility and stability to individuals with lower limb amputation. It interfaces to the user by attaching to their socket via an industry-standard pyramid connector. | Device: DSR Ankle<br>* This is the experimental ankle component used in the overall prosthetic intervention.<br>* Other names: The Damping, Stiffness and Repositioning Ankle;|
| Active Comparator: Predicate Ankle<br>The predicate ankle is the user's prescribed prosthesis worn for the activities of daily living. | Device: Predicate Ankle<br>* This is the participant's prescribed ankle/foot complex used in the overall prosthetic intervention.<br>* Other names: Daily Use Ankle;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Minimum Foot Clearance | Minimum foot clearance is the shortest distance between the foot and the ground during swing, and it occurs approximately halfway through the swing phase of gait. | after up to 3 weeks of training | 
| Time to Foot Flat | Time to foot flat is the duration of time between initial contact at heel strike and the full contact of the sole of the foot on the ground in stance. | after up to 3 weeks of training | 
| Maximum Lyapunov Exponent | The maximum Lyapunov exponent is a measure of dynamic gait stability that uses nonlinear time series analysis. | after up to 3 weeks of training | 
| Weight Bearing Symmetry | Weight bearing symmetry is a measure of standing stability represented by the ratio of left to right side weight bearing. | after up to 3 weeks of training | 
| Center of Pressure RMS Velocity | Center of pressure RMS velocity is measured by calculating the velocity of the COP from force plate data while standing. | after up to 3 weeks of training | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Orthotics Prosthetics User Survey (OPUS) | The OPUS is a self-report questionnaire consisting of 5 modules. It can be used for prosthetic and orthotic programs for quality assessment, to maintain awareness of improvement in activities, to evaluate changes in patient's functional status and quality of life, and to assess satisfaction with devices and services. | after up to 3 weeks of training | 
| Numerical Pain Rating Scale (NPRS) | The NPRS is a segmented numeric version of the visual analog scale (VAS) in which a respondent selects a whole number (0-10 integers) that best reflects the intensity of his/her pain. | after up to 3 weeks of training | 
| Borg Rating Scale (RPE) | The RPE is a tool for measuring an individual's effort and exertion, breathlessness and fatigue during physical work. | after up to 3 weeks of training | 
| Modified Falls Efficacy Scale (mFES) | The mFES indicates the level of perceived confidence an individual has about carrying out everyday activities without falling. The modified version includes outdoor activities. | after up to 3 weeks of training | 
| 10 Meter Walk Test (10 MWT) | The 10 MWT assesses walking speed in meters per second over a distance of 10 meters. | after up to 3 weeks of training | 
| Six Minute Walk Test (6 MWT) | The 6 MWT assesses walking distance in meters over a period of 6 minutes. | after up to 3 weeks of training | 
| Berg Balance Test (BBS) | The BBS is used to objectively determine a patient's ability to safely balance during a series of predetermined tasks. It is a 14 item list with each item consisting of a five-point ordinal scale ranging from 0 to 4, with 0 indicating the lowest level of function and 4 the highest level of function and takes approximately 20 minutes to complete. | after up to 3 weeks of training | 
| Functional Gait Assessment (FGA) | The FGA is used to assess postural stability during walking and assesses an individual's ability to perform multiple motor tasks while walking. | after up to 3 weeks of training | 
| Hill Assessment Index (HAI) | The HAI is scored on an ordinal scale from 0 to 11 and measures the patient's ability to navigate sloped terrain. | after up to 3 weeks of training | 
| Timed Up and Go (TUG) | The TUG assesses mobility, balance, walking ability, and fall risk in older adults. | after up to 3 weeks of training | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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K2, Amputation, Transtibial, Limited Community Ambulator