C-Leg 3 and C-Leg 4 Study in Transfemoral Amputees

Study Overview
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Brief Summary
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The aim of this post-market study is to confirm that the microprocessor controlled prosthetic knee components (C-Leg 3 and C-Leg 4) in comparison to mechanical knee joints can bring additional benefit to the users primarily on level walking and secondarily in safety, stair and hill mobility, activities of daily living, satisfaction and preference.

Detailed Description
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During the last two decades many microprocessor controlled knee joints (MPK) appeared on the market.The newly developed C-Leg 4 aims to provide improved standing function while in the same time offering technology of knee´s previous version (C-Leg 3). Since added functional benefit of a knee joint cannot be anticipated just due to the fact that the knee is controlled by the microprocessor, the aim of this post-market study is to evaluate the safety, functional mobility and satisfaction of the microprocessor controlled prosthetic knee components C-Leg 3 and C-Leg 4 in comparison to mechanical knee joints. Additional goal is to improve the methodological quality of research conducted in the field.

Official Title
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A Randomized, Blinded, Cross-over Trial to Evaluate the Safety, Functional Mobility and Satisfaction of the Microprocessor Controlled Prosthetic Knee Component C-Leg 4 in Transfemoral Amputees

Conditions
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Lower Limb Amputation Above Knee (Injury)

Intervention / Treatment
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* Device: C-Leg 4
* Device: C-Leg 3


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Person is >18 years old. Person is a unilateral transfemoral or knee-disarticulation amputee with stabilized residual limb. Person is a K2, K3 or K4 ambulator based on Medicare Functional Classification Level (MFCL). Person is currently fitted with a prosthesis using a non-microprocessor controlled prosthetic knee for at least 6 months. Person was never fitted with microprocessor controlled prosthetic knee joint. Person is willing and able to independently provide informed consent. Person is willing to comply with study procedures. Person wears prosthesis daily and ≥ 8 hours/day. Person is walking on average 1km/day. Person is walking not slower than 3km/h ( 0.8m/s) (based on 10m walk test conducted during recruiting). Person is walking on level ground in a step over step manner. Exclusion Criteria: Person is under 18 years of age. Person who weighs more than 136kg. Person who weighs less than 50kg. Person who is pregnant. Person has a history of chronic skin breakdown on the residual limb. Person has conditions that would prevent participation and pose increased risk (e.g. unstable cardiovascular conditions that preclude physical activity such as walking). Person falls ≥ once a week due to the reasons that could not be corrected by the new prosthesis (for ex. problems with vestibular system). Person is using under arm axillary crutches or walker. Person in an emergency, life threatening situation. Person is unwilling/unable to follow instructions. Person who is not available to follow the entire study protocol. Person who is participating in another study or intends to participate in another study during this study duration. Person who cannot personally provide their consent. Person who is not wearing prosthesis 8hours/day on average. Person who has a score on 10m walk test less than 3km/h ( 0.8m/s) (based on 10m walk test conducted during recruiting). Person who walks on average less than 1km per day. Person who is not able to walk on level ground in a step over step manner.

Ages Eligible for Study
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Minimum Age: 18 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: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: C-Leg 3, then C-Leg 4<br>Participants are first fitted with a C-Leg 3, receive physical therapy, acclimate for 90 days and are then assessed in the clinic. They then receive a C-Leg 4, receive additional physical therapy and acclimate for 30 days after which they are again assessed in the clinic. | Device: C-Leg 4<br>* Microprocessor Controlled Knee<br>Device: C-Leg 3<br>* Microprocessor Controlled Knee<br>|
| Experimental: C-Leg 4, then C-Leg 3<br>Participants are first fitted with a C-Leg 4, receive physical therapy, acclimate for 90 days and are then assessed in the clinic. They then receive a C-Leg 3, receive additional physical therapy and acclimate for 30 days after which they are again assessed in the clinic. | Device: C-Leg 4<br>* Microprocessor Controlled Knee<br>Device: C-Leg 3<br>* Microprocessor Controlled Knee<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in 6 Minute Gait Test | A measure of walking endurance, the distance walked in meters after 6 minutes. | Baseline and after acclimation period (30-90 days after fitting) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in 10 Meter Gait Test | Average gait speed over middle 6 meters of a 10-meter course at both self-selected and fastest safe walking speeds | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Stairs Assessment Index (SAI) | Participants are scored on a 14-level scale for independence, technique and step length for ascending and descending a 12-step ADA-compliant stairwell. The maximum score is 13 and the minimum 0. Higher scores indicate greater independence. Time to descend stairs was also recorded. | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Hill Assessment Index (HAI) | Participants are scored on a 12-level scale for independence, technique and step length for descending a 5m, 5-degree downgrade hill at self selected speed. The maximum score is 11 and the minimum 0. Higher scores indicate greater independence. Time to descend the hill was also recorded. | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Four Step Square Test (FSST) | Time to complete a stepping sequence through 4 squares as quickly as possible. The test involves stepping forward, backward and sideways to the left and right while face the same direction. | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Activities-specific Balance Confidence (ABC) Scale | Assessment of patient-perceived balance confidence for 16 activities of daily living. For each activity, subjects rate their level of confidence in doing the activity without losing their balance or becoming unsteady on a scale from 0% to 100%, with 100% being the highest level of confidence. The total score for the ABC scale is an average of all activity scores. | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Prosthetic Limb Users Survey of Mobility (PLUS-M) | The PLUS-M 12-item short form is a valid and reliable self-reported measure for the mobility of adults with lower limb amputations. PLUS-M asks about the patient's ability to perform simple and complex tasks. Higher PLUS-M scores correspond with greater mobility. T-scores range from 21.8 to 71.4. A T-score has a mean of 50 and a standard deviation (SD) of 10. A PLUS-M T-score of 50 represents the mean mobility reported by the development sample (i.e., people with unilateral amputation). | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Amputee Body Image Scale (ABIS) | The ABIS assesses how an amputee perceives and feels about his or her body experience. The scale addresses several different domains, including: 1) body appearance; 2) body function; 3effective distress; and 4) behavioral avoidance in social situations. The scale produces scores that range from 1 to 100, with low scores indicating the relative absence of a body image concern and higher scores indicating the presence of a more serious body-image concern. | Baseline and after acclimation period (30-90 days after fitting) | 
| Change in Number of Stumbles and Falls | Stumbles and falls in the previous 30 days for each studied device based on records in a subject log book. At baseline, users were asked to recall the number of stumbles and falls in the previous 30 days. | Baseline and after acclimation period (30-90 days after fitting) | 
| Preference of the Knee (Percentage of Subjects That Preferred Each Studied Knee) | The user´s knee preference is assessed with the question: Which prosthesis do you prefer? | At 3rd study visit after having been fitted and acclimatized to each of the study devices |