Clinical Outcomes With Non-Powered vs. Powered Prosthetic Knees by K2-level Amputees

Clinical Outcomes Associated With At Home Use of Non-Powered vs. Powered Prosthetic Knees by K2-level Individuals With Transfemoral Amputations

The goal of this proposed project is to gather community-based data from the K2-level Transfemoral Amputee (TFA) population to aid in evidence-based prescription of powered prosthetic knees (i.e., choosing the right device to maximize the benefit for each patient). The investigators intend to use this trial data along with a concurrent study being conducted within the K3-K4 level population to guide the implementation of effective prescriptions towards those that can benefit most from a given device and limit prescription to those who would not see benefit in order to ensure the most judicious use of Department of Defense (DoD) and Veteran's Affairs healthcare dollars. The findings will also be shared with the research community to help drive the design of future devices by identifying what features and functions are most beneficial to which patient populations when the devices are used outside of the laboratory. In summary, more community-based data on how powered prosthetic knees compare with the current standard in TFA populations is needed to allow for improved clinical decision making and clinical outcomes.

Study Overview

• Status: Recruiting
• Conditions: Lower Limb Amputation Above Knee (Injury); Amputation; Prosthesis User; Amputation; Traumatic, Leg, Lower; Limb; Absence, Congenital, Lower; Amputation; Traumatic, Leg: Thigh, Between Hip and Knee
• Intervention / Treatment: Device: Ossur Power Knee; Device: Reboocon Intuy Knee

Detailed Description

This study will focus on investigating the tradeoffs between powered knees and mechanical knees to identify the prosthetic knee that is best suited for K2 users during different tasks. The investigators will assess measured, observed, and self-reported outcomes achieved through real-world use of these prosthetic knees.

The results of this study will (1) provide initial evidence to guide clinical prescription and use of powered knee technologies for K2-level individuals with sound scientific data, (2) provide pilot data for a larger clinical trial to further inform the evidence-based prescription of powered knee technologies to other K-levels, and (3) obtain data that can be disseminated to other researchers and inform the design of future powered prosthetic knees by understanding the needs of users and identifying the features and functions that are most valuable to this patient population, as well as evaluating the capabilities and limitations of current devices.

The investigators plan to perform a pilot longitudinal randomized crossover study to compare the effects of power at the knee in individuals with unilateral transfemoral amputation. The three interventions, or conditions, to be tested are: (A) the Össur Power Knee, a powered knee that has recently released its third version, (B) The Reboocon Intuy Knee, a newly commercialized powered knee, and (C) the Össur OFM-2, a passive mechanical knee, and the most commonly used knee for K2 users. The two powered knees being tested differ in aspects such as max power/torque, weight, algorithm, and battery life. Therefore, this study will not only provide insights to the role powered knees play in the K2 population, but also if certain aspects of each powered knee are more preferred or accepted by patients in order to inform future powered knee developments and clinical treatment.

The order of the knee conditions will be randomized across subjects. Block randomization using a previously developed custom program based on random number generation will be used to equally distribute the subjects into the 6 possible intervention orders (ABC, ACB, BAC, BCA, CAB, CBA). For each condition, the subject will be trained on and acclimated to the device during the first month of the take-home period, and then will continue to wear it at home for two more months for a total of three months per condition. There may be seasonal effects due to the timing of when the various test conditions are administered, however, the investigators plan to offset these effects with condition randomization, multiple site testing, and staggered start times.

Testing will consist of test sessions, training sessions, at-home wear of the device, and functional and self-report assessment for each intervention condition.

After receiving IRB approval, subjects will be recruited and screened for eligibility. If they are eligible and decide to participate, they will be scheduled for their first site visit. They will either be consented over the phone before their first site visit or at the first site visit. If over the phone, study staff will use the telephone script to confirm eligibility and guide the subject through consent form details. Subjects will be given the informed consent form to read through entirely before signing and are encouraged to ask questions at any time.

Each subject will be provided with a standardized commercially available prosthetic ankle/foot appropriate for K2-ambulators (e.g., Össur Pro-Flex LP), to wear throughout all study periods for comparability between subjects and conditions.

Prior to each condition, each subject will be fit and aligned on the knee by a trained certified prosthetist. An activity monitor (such as the GeneActiv™) will be worn by the subject. As the investigators have done in prior studies, they will use the activity monitor to track the number of steps the subjects take during each condition.

The subject will wear the knee being tested at home for three months. During the first month of each condition, subjects will acclimate to the knee and participate in at least four, but up to eight, 1-hour training sessions. At a minimum, each subject will receive three training sessions to learn how to properly use each device for a variety of daily activities and a fourth session to demonstrate retention of the learned skills. Subjects will continue training until they show retention of the understanding and/or proficiency of the device functions or until they have received eight training sessions, whichever comes first. After eight training sessions, they will have completed all of the available training and will therefore continue with the study at their current proficiency level. Functional tests and self-report surveys will be administered at the first and last training sessions to evaluate changes in these metrics caused by the training. For each condition, the investigators will work with trained and experienced clinicians, and prosthetic knee manufacturers as needed, to develop the training protocol and determine proficiency. At the last training session, the subject will complete a subset of the outcomes and self-report measures in order to collect and compare data from before and after the subject gets trained on each knee condition.

Subjects will be asked to continue to wear the knee full time for the remainder of the three-month take-home period. The investigators will call the patient periodically to ask them whether they have experienced a recent fall. If they respond positively that they had a fall, follow-up questions may be asked via a standardized fall questionnaire similar to those used in prior studies to get more specific details. After three months of at-home wear, the subject will return for the second test visit. During that visit, functional tests and self-report surveys will be administered on the first knee. Afterwards, the fitting, training, at home wear, and in-clinic assessments described above will be repeated for the second and third knee conditions.

• Study Type: Interventional
• Enrollment (Estimated): 26
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Shane Wurdeman, PhD; Phone Number: 402-290-8051; Email: swurdeman@hanger.com
• Study Contact Backup: Name: Jennifer Johansson, MS; Phone Number: 774-233-0874; Email: jen.johansson@liberatingtech.com

Study Locations

• United States
  • Texas
    • Austin, Texas, United States, 78758
      • Recruiting
      • Hanger Clinic
      • Contact: Shane Wurdeman, PhD; Phone Number: 402-290-8051; Email: swurdeman@hanger.com
      • Contact: Siya Asatkar; Phone Number: 512-774-7105; Email: sasatkar@hanger.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Are at least 18 years old
• Transfemoral prosthesis user (limb absence between the knee and hip)
• Current user of a mechanical knee
• Regularly wears prosthesis at least 5 days per week
• Have adequate clearance between distal end and ground for necessary knee and foot components
• Current Medicare Functional Classification Level (K-Level) of 2 as determined by the healthcare team
• Socket-Comfort Score: 6 or above to ensure adequate socket fit
• Six months or more experience on a prosthesis
• Body weight between 50kg and 116kg (110lbs - 256lbs)
• Height between 1.2m and 1.95m (47.2in and 76.8in)
• Has a phone to answer periodic study calls

Exclusion Criteria:

• Present injuries to residual limb or contralateral leg affecting functional ability
• Contralateral amputation proximal to MTP (metatarsophalangeal) joint
• Socket issues/changes in the last 6 weeks
• Users with bone-anchored implants
• Health or medical condition, diagnosis, or other cause that would prevent participant from effectively following study protocol, performing required outcome measures, and/or completing the study

Subjects can be excluded at the discretion of the investigator for other unforeseen disqualifying criteria (such as specific cognitive issues, etc.).

If subjects experience a health or medical condition that leaves them immobile for more than 2 weeks, they may be given the option to restart the study condition upon recovery, as long as eligibility criteria is still met, and comparable baseline functionality is demonstrated with outcomes measures.

Using a knee that the subject is unfamiliar with may increase the risk of falling. Therefore, pregnant women should not participate in the study and will be screened by self-disclosure.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Comparator Baseline; The subject will wear the Ossur OFM-2, a passive mechanical knee which is the most commonly used knee for K2 users, for 3 months, as well as in the lab to complete outcome measures.
Experimental: Ossur Power Knee; The subject will wear the Ossur Power Knee for 3 months, as well as in the lab to complete outcome measures.	Device: Ossur Power Knee; Newest version of the commercially-available powered knee developed by Ossur.; Other Names: Ossur Power Knee III; PK3
Experimental: Reboocon Intuy Knee; The subject will wear the Reboocon Intuy Knee for 3 months, as well as in the lab to complete outcome measures.	Device: Reboocon Intuy Knee; Commercially-available powered knee developed by Reboocon.; Other Names: Intuy Knee

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Step count	Prior to each condition, each subject will be fit and aligned on the designated knee by a trained certified prosthetist. An activity monitor (such as the GeneActiv™) will be worn by the subject during each 3 month intervention period. Similar to prior studies, the investigators will use the activity monitor to track the number of steps the subjects take in each condition. A higher step count is a better outcome.	Monitored over entire study (9 months)
Activities-Specific Balance Confidence scale (ABC) - Measuring change from baseline	The ABC is a structured questionnaire that measures an individual's confidence during ambulatory activities without falling or experiencing a sense of unsteadiness. It consists of 16 questions gauging the individual's confidence while doing activities, from 0 (no confidence) to 4 (complete confidence). A higher score means a better outcome. This survey will be given at the beginning and end of each study condition (3 conditions, 3 months per condition). Additionally, this survey will be given at the subject's last training session, which is dependent on the subject's scheduling availability and proficiency with each knee condition. The subject will have between 4-8 training sessions per condition until deemed proficient or the 8th session has been completed, whichever comes first. All training sessions are expected to be completed within the first month of each condition. This survey will be administered as a part of the master questionnaire.	Throughout study completion, an average of 9 months
Prosthesis Evaluation Questionnaire - Well Being (PEQ-WB) - Measuring change from baseline	The version of the PEQ which will be administered consists of 2 questions in 1 category (well being). For purposes of easier administration, the investigators have adopted the modified 10-point ordinal scale version of the PEQ-WB (scale 1-10, where a higher score is a better outcome). This survey will be given at the beginning and end of each study condition (3 conditions, 3 months per condition). Additionally, this survey will be given at the subject's last training session, which is dependent on the subject's scheduling availability and proficiency with each knee condition. The subject will have between 4-8 training sessions per condition until deemed proficient or the 8th session has been completed, whichever comes first. All training sessions are expected to be completed within the first month of each condition. This survey will be administered as a part of the master questionnaire.	Throughout study completion, an average of 9 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Two Minute Walk Test (2MWT) - Measuring change from baseline	The 2MWT is a measure of self-paced walking ability and functional capacity, particularly for those who cannot manage the longer Six Minute Walk Test (6MWT) or 12 Minute Walk Test. Participants will walk a set circuit for a total of two minutes. The distance covered over a time of 2 minutes is used as the outcome by which to compare changes in performance capacity. This assessment may be performed at each site visit.	Throughout study completion, an average of 9 months
Stair Assessment Index (SAI)	The Stair Assessment Index (SAI) is an observational outcome measure designed to assess an individual's ability to ascend and descend stairs. The SAI is a 14-level ordinal scale that spans a functional continuum from choosing not to ascend or descend the stairs to a fully independent step-over-step stair gait. A SAI rating is independently assigned to the activities of stair ascent and stair descent. These ratings reflect the individual's degree of independence and quality of movement in stair gait. The 14 ratings of the SAI are based on several central characteristics of stair gait including the ability to perform the task, the need for assistance, the use of an assistive device, and the gait style chosen to perform the task. A higher score means a better outcome. This assessment may be performed at each site visit.	Start of study (0 months), 3 months, 6 months, 9 months
Timed Up and Go (TUG) Test	The Timed Up and Go (TUG) test may be used to measure physical mobility, assess fall risk, and predict prosthetic nonuse in patients with a lower-limb amputation who are using a prosthesis. In the timed up and go (TUG) test, subjects are asked to rise from a standard armchair, walk to a marker 3 m away, turn, walk back, and sit down again. The test is timed in seconds using a stopwatch. A lower time means a better outcome. The test is a reliable and valid test for quantifying functional mobility that may also be useful in following clinical change over time. This assessment may be performed at each site visit.	Throughout study completion, an average of 9 months total.
Patient Reported Outcomes Measures Information System - Physical Function (PROMIS-PF)	The form being administered is PROMIS Physical Function short form 10b. PROMIS Physical Function (PROMIS PF) measures the outcome of patients or clients by assessing physical function through a grading scale of activities of daily living. PROMIS PF is used as an outcome in research on the effectiveness of interventions. The questions are answered on a scale from 1-5, with 1 being 'unable to do' and 5 being 'able to do without difficulty', pertaining to an activity. A higher score means a better outcome. This survey will be administered as a part of the master questionnaire.	Start of study (0 months), 3 months, 6 months, 9 months
Prosthetic Limb Users Survey of Mobility (PLUS-M) 20 Item Custom Short Form - Measuring change from baseline	This version of the PLUS-M is a 20 item short form customized with a set of questions pertinent to the K2 population. The scores are directly comparable to other versions of the PLUS-M. Responses are scored from 1-5, with 1 being 'unable to do' and 5 being 'without any difficulty', pertaining to an activity. A higher score means a better outcome. The scores will be added together to make the 'raw score', which can then be translated to T-score, Standard Error, and percentile. This survey will be given at the beginning and end of each study condition (3 conditions, 3 months per condition), as well as at the subject's last training session. The subject will have between 4-8 training sessions per condition until deemed proficient or the 8th session has been completed, whichever comes first. All training sessions are expected to be completed within the first month of each condition. This survey will be administered as a part of the master questionnaire.	Throughout study completion, an average of 9 months total.
Borg Rating of Perceived Exertion (Borg RPE)	The Borg Rating of Perceived Exertion (Borg RPE) is a way of measuring physical activity intensity level. Perceived exertion is how hard the participant feels like their body is working. The original scaling is from 6-20, corresponding to approximate heart rate (x10 beats per minute). The investigators will be using the adapted Borg CR10 scale, which scales from 0-10 (0=no exertion at all, 10=maximal exertion). A higher score means a worse outcome.	Start of study (0 months), 3 months, 6 months, 9 months
Patient Reported Outcomes Measures Information System - Fatigue (PROMIS-FAT)	The form being administered is PROMIS Fatigue short form 8a. The PROMIS Fatigue item banks assess a range of self-reported symptoms, from mild subjective feelings of tiredness to an overwhelming, debilitating, and sustained sense of exhaustion that likely decreases one's ability to execute daily activities and function normally in family or social roles. Fatigue is divided into the experience of fatigue (frequency, duration, and intensity) and the impact of fatigue on physical, mental, and social activities. The fatigue short forms are universal rather than disease-specific. All assess fatigue over the past seven days. The questions are answered on a scale from 1-5, with 1 being "not at all" or "never", and 5 being "very much" or "always". A higher score means a worse outcome. This survey will be administered as a part of the master questionnaire.	Start of study (0 months), 3 months, 6 months, 9 months
Self reported falls	The investigators will call the patient at most weekly to ask them whether they have experienced a recent fall. If the subject responds positively that they had a fall, follow-up questions may be asked via a standardized fall questionnaire similar to those used in prior studies to get more specific details. A higher number of falls means a worse outcome. The subject may be asked to provide additional notes periodically to document their problems, experiences, and feedback.	Throughout study completion, an average of 9 months total
Patient Reported Outcomes Measures Information System - 29 (PROMIS-29)	The PROMIS-29 is a short form assessment containing four items from each of seven PROMIS domains (Depression, Anxiety, Physical Function, Pain Interference, Fatigue, Sleep Disturbance, and Ability to Participate in Social Roles and Activities) which are all scaled from 1-5 , plus one pain intensity question (0-10 numeric rating scale). This survey will be administered as a part of the master questionnaire. For the Physical Function, Ability to Participate in Social Roles and Activities, and Cognitive Function domains, a higher score means a better outcome. For the Anxiety, Depression, Fatigue, Sleep Disturbance, Pain Interference, and Pain Intensity domains, a higher score means a worse outcome.	Start of study (0 months), 3 months, 6 months, 9 months
Oswestry Disability Index (ODI)	The Oswestry Disability Index is a tool that researchers and disability evaluators use to measure a patient's permanent functional disability. The patient is asked 10 questions, each with 6 possible answers. The answers are scored 0-5. The total score corresponds to disability level (no disability, mild disability, moderate disability, severe disability, completely disabled). A higher score means a worse outcome. This survey will be administered as a part of the master questionnaire.	Start of study (0 months), 3 months, 6 months, 9 months
Patient Reported Outcomes Measures Information System - Ability to Participate in Social Roles and Activities (PROMIS-APSRA)	The PROMIS-APSRA is a short form that assesses an individual's perceived ability to perform their usual social roles and activities. The form being administered is PROMIS-APSRA short form 8a. The questions are answered on a scale from 1-5, with 1 being "never", and 5 being "always". A higher score means a better outcome. This survey will be administered as a part of the master questionnaire.	Start of study (0 months), 3 months, 6 months, 9 months

Collaborators and Investigators

• Sponsor: Liberating Technologies, Inc.
• Collaborators: Hanger Clinic: Prosthetics & Orthotics
• Investigators: Principal Investigator: Jennifer Johansson, MS, Liberating Technologies, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): September 12, 2023
• Primary Completion (Estimated): August 31, 2026
• Study Completion (Estimated): August 31, 2026

Study Registration Dates

• First Submitted: December 22, 2023
• First Submitted That Met QC Criteria: December 22, 2023
• First Posted (Actual): January 8, 2024

Study Record Updates

• Last Update Posted (Estimated): September 3, 2025
• Last Update Submitted That Met QC Criteria: September 2, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: amputee; lower limb amputee; transfemoral amputee; prosthetic knee; power knee; lower limb prosthesis user; mechanical knee
• Additional Relevant MeSH Terms: Wounds and Injuries; Wounds and Injuries
• Other Study ID Numbers: 10877

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No