Assist-Knee: Energy-Harvesting Knee Prosthesis

Study Overview
=================
Brief Summary
-----------------
The purpose of this research is to validate the Assist-Knee design and function by collecting pilot data during the stand-to-sit-to-stand transition in transfemoral prosthesis users when using the Assist-Knee to harvest energy and return energy .

Official Title
-----------------
Evaluation of an Energy-Harvesting Knee Prosthesis in Transfemoral Prosthesis Users

Conditions
-----------------
Transfemoral Amputation, Artificial Limbs

Intervention / Treatment
-----------------
* Device: Assist-Knee
* Device: Habitual Prosthesis


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Unilateral transfemoral limb loss At least one year post-amputation and currently successfully using a prosthesis Uses modular endoskeletal prosthetic components Has bilateral normal range of motion Ability to perform the following activities: Walking ability or ability to take steps over 10 meters Upright standing stability Stand-to-sit stability (i.e. go from a standing position to a seated position independently) Sit-to-stand stability (i.e. rise from a seated position independently) Ability to communicate individual perceptions in the English language Ability to provide informed consent Exclusion Criteria: Confounding injury or musculoskeletal problem Pregnancy Lower limb peripheral neuropathy Symptomatic cardiovascular disease or chronic obstructive pulmonary disease Not able to read and understand English Use of assistive devices for sit-to-stand and stand-to-sit (e.g. canes, walkers)

Ages Eligible for Study
-----------------
Minimum Age: 21 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Device Feasibility
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Crossover clinical trial
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Habitual Prosthesis<br>Participant's prescribed prosthesis | Device: Habitual Prosthesis<br>* Habitual baseline prosthesis prescribed by participant's clinician.<br>|
| Experimental: Assist-Knee<br>Experimental knee prosthesis | Device: Assist-Knee<br>* Assist-Knee is an experimental lower limb knee prosthesis.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to Complete Sit-to-Stand | The amount of time, measured in seconds, needed by the subject to complete the sit-to-stand transition. At least four trials of the sit-to-stand maneuver were collected for each participant using a motion analysis system. Average and standard deviation of the time to complete the sit-to-stand transition were calculated for each participant (each participant served as their own control in this pilot study). The start of the transition was determined by participant initiation; the end of the transition was determined by the participant reaching full knee extension. | Collection at baseline | 
| Time to Complete Sit-to-Stand | The amount of time, measured in seconds, needed by the subject to complete the sit-to-stand transition. At least four trials of the sit-to-stand maneuver were collected for each participant using a motion analysis system. Average and standard deviation of the time to complete the sit-to-stand transition were calculated for each participant (each participant served as their own control in this pilot study). The start of the transition was determined by participant initiation; the end of the transition was determined by the participant reaching full knee extension. | After acclimation to Assist-Knee (Participants are given at least 10 minutes and no more than 60 minutes to acclimate to each Assist-Knee condition for safety. After acclimating, participants will complete the maneuver to measure this outcome.) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Timed Up and Go (TUG) Test | The Timed Up and Go (TUG) test is a validated timed functional test that involves standing up from a chair, walking forward for 3 meters, turning around, walking back to the chair for 3 meter, and sitting down. Each participant completed the TUG test for three trials. Time was measured using a stopwatch. Average and standard deviation of the time to complete the TUG test were calculated for each participant (each participant served as their own control in this pilot study). | Collection at baseline | 
| Timed Up and Go (TUG) Test | The Timed Up and Go (TUG) test is a validated timed functional test that involves standing up from a chair, walking forward for 3 meters, turning around, walking back to the chair for 3 meter, and sitting down. Each participant completed the TUG test for three trials. Time was measured using a stopwatch. Average and standard deviation of the time to complete the TUG test were calculated for each participant (each participant served as their own control in this pilot study). | After acclimation to Assist-Knee (Participants are given at least 10 minutes and no more than 60 minutes to acclimate to each Assist-Knee condition for safety. After acclimating, participants will complete the maneuver to measure this outcome.) | 
| Time to Complete Stand-to-Sit | The amount of time, measured in seconds, needed by the subject to complete the stand-to-sit transition. At least four trials of the stand-to-sit maneuver were collected for each participant using a motion analysis system. Average and standard deviation of the time to complete the stand-to-sit transition were calculated for each participant (each participant served as their own control in this pilot study). The start of the transition was determined by participant initiation; the end of the transition was determined by the participant being seated on a chair. | Collection at baseline | 
| Time to Complete Stand-to-Sit | The amount of time, measured in seconds, needed by the subject to complete the stand-to-sit transition. At least four trials of the stand-to-sit maneuver were collected for each participant using a motion analysis system. Average and standard deviation of the time to complete the stand-to-sit transition were calculated for each participant (each participant served as their own control in this pilot study). The start of the transition was determined by participant initiation; the end of the transition was determined by the participant being seated on a chair. | After acclimation to Assist-Knee (Participants are given at least 10 minutes and no more than 60 minutes to acclimate to each Assist-Knee condition for safety. After acclimating, participants will complete the maneuver to measure this outcome.) | 
| Percentage of Body Weight on Contralateral Limb at 65 Degrees Knee Flexion | The percentage of body weight on the contralateral limb was determined for both stand-to-sit and sit-to-stand transitions at 65 degrees knee flexion. A force plate under the contralateral limb recorded the amount of loading on the limb during the stand-to-sit and sit-to-stand transitions. The amount of contralateral limb loading at 65 degrees knee flexion was determined and divided by the participant's total loading due to overall body weight. This value was then converted to a percentage. | Collection at baseline | 
| Percentage of Body Weight on Contralateral Limb at 65 Degrees Knee Flexion | The percentage of body weight on the contralateral limb was determined for both stand-to-sit and sit-to-stand transitions at 65 degrees knee flexion. A force plate under the contralateral limb recorded the amount of loading on the limb during the stand-to-sit and sit-to-stand transitions. The amount of contralateral limb loading at 65 degrees knee flexion was determined and divided by the participant's total loading due to overall body weight. This value was then converted to a percentage. | After acclimation to Assist-Knee (Participants are given at least 10 minutes and no more than 60 minutes to acclimate to each Assist-Knee condition for safety. After acclimating, participants will complete the maneuver to measure this outcome.) |