Effects of Microprocessor-controlled Prosthetic Knees on Fall-related Health Outcomes in Limited Community Ambulators

Not Applicable

Not yet recruiting

• Conditions: Amputation; Prosthesis User; Amputation; Traumatic, Leg: Thigh, Between Hip and Knee; Limb; Absence, Congenital, Lower; Lower Limb Amputation Above Knee (Injury); Lower Limb Amputation Above Knee

• Registration Number: NCT06937242
• Lead Sponsor: Hanger Institute for Clinical Research and Education, LLC

Brief Summary

The goal of this study is to find out if using microprocessor-controlled prosthetic knees (MPKs), prosthetic knees with a built-in computer, improves health outcomes related to falls in adults who use above-knee prostheses. The main questions are:

* Do individuals with MPKs have fewer fall-related health issues compared to those with non-microprocessor-controlled prosthetic knees (nMPKs)?

* Do individuals with MPKs have increased mobility, faster walking speed, and improved quality of life compared to those with nMPKs?

Participants who have recently received an nMPK as part of their regular care can join the study. Those randomized to the control group will keep using their nMPK, while those randomized to the intervention group will receive a stance-and-swing MPK or a stance-only MPK.

Detailed Description

This study aims to assess the effects of microprocessor-controlled prosthetic knees on fall-related health outcomes in prosthesis users classified as limited community ambulators. This study also seeks to expand the existing research on the potential microprocessor-controlled prosthetic knees (MPKs) have on improving health outcomes for patients who are classified as limited community ambulators (i.e., Medicare Functional Level K2). The investigators will examine whether the anticipated reduction in falls in K2 users is accompanied by improvements in fall-related health outcomes like fall-related anxiety, fall-related self-efficacy, fall-related avoidance behaviors, fall-related interference, and fewer falls. Investigators will also examine whether MPK use in the K2 population leads to increased mobility, increased walking speed, and improvements in health-related quality of life.

A 12-month, pragmatic randomized control trial (pRCT) will be conducted to assess whether MPKs improve fall-related health outcomes in unilateral, transfemoral or knee disarticulation prosthesis users classified as limited community ambulators.

Patients will be invited to participate in the trial as a part of their routine prosthetic care. If a patient agrees to participate and is eligible, a follow-up appointment will be scheduled, and the patient will be consented by the research study team. Participants will then be randomized to the intervention or control group. Participants in the control arm of the trial will remain in their prescribed prosthesis with a non-microprocessor knee (nMPK). Participants randomized to the intervention arm of the trial will have their nMPK exchanged for either a stance-and-swing MPK (Ottobock C-Leg 4) or a stance-only MPK (Ottobock Kenevo). The MPK provided to each participant in the intervention arm will be determined by the manufacturer's recommended patient-selection criteria. Transfemoral prosthesis users walking up to 0.83m/s (3km/hr) in the 2-minute walk test (2MWT) will receive a stance-only MPK (Kenevo), while participants walking more than 0.83m/s in the 2MWT will receive a stance-and-swing MPK (C-Leg 4). Study participants will wear the knee for 12 months.

Each participant will be assessed at baseline (after enrollment and randomization), and 1-, 3-, 6-, 9-, and 12-months after baseline. The baseline and 12-month assessments will be the primary study time points. T-scores on the Prosthetic Limb Users Survey of Fall-Related Health (PLUS-F) and number of fall events experienced over the prior year will serve as the primary endpoints. Participants will complete a selected set of performance-based tests and standardized self-report surveys. In addition to the outcome measures noted, investigators will collect sociodemographic, health, amputation, fall history, and prosthesis information by self-report in order to characterize study participants and assess the comparability of the study groups. Fall-related health outcomes (e.g. fall-related self-efficacy and fall-related interference) will be measured using new PLUS-F instruments as well as existing measures that measure fall-related outcomes. We will also co-administer the Prosthetic Limb Users Survey of Mobility (PLUS-M) to assess participants' prosthesis-related mobility. Walking speed, mobility, endurance, and quality of life will be measured. For the 6- and 12-month assessments, we will also collect the hours of wear and hours of activity in the prosthesis.

Participants in both groups will receive education and training specific to their prosthetic knee between assessment 1 (baseline) and assessment 2 (one-month follow-up). Training will consist of 1 to 4 sessions to facilitate participants' use of their assigned prostheses. The number of sessions will be determined by the ability of each participant to explain and/or perform specified tasks. A standardized protocol and training checklist will be developed by our team Physical Therapist specific to each condition in collaboration with the knees' manufacturer (Ottobock). Every 2 weeks, throughout the 12 months of patient participation, the number of falls and near-fall events, including the event, injury, treatment and/or hospitalization, and whether the falls occurred while wearing the prosthesis, will be collected.

Study Timeline

• Status Verified: 2025-04
• Study Start: 2025-04
• Study First Submitted: 2025-04-11
• Study First Submitted QC: 2025-04-17
• Last Update Submitted: 2025-04-21
• Study First Posted: 2025-04-22
• Last Update Posted: 2025-04-24
• Primary Completion: 2027-02
• Study Completion: 2027-02

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 100

Inclusion Criteria

• Unilateral transfemoral or knee disarticulation limb loss.

• 12 months or longer since time of limb loss.

• Current user of a prosthesis with a non-microprocessor-controlled prosthetic knee.

• Received a replacement prosthesis with a non-microprocessor knee in the past 4-24 months.

• Clinician has deemed patient limited community ambulator (Medicare functional classification level K2).

• In addition, Medicare functional classification level K2 as determined by at least one of the following criteria:

  1. Houghton Score: 5-10
  2. Prosthetic Limb Users Survey of Mobility (PLUS-M) T-Score: if amputation etiology is vascular disease/diabetes <49.45, otherwise, <36.75.
  3. Amputee Mobility Predictor (AMPPRO) score: 27-42 collected within the last 24 months

• Ability to read, write, and understand English.

Exclusion Criteria

• Any health condition that would prevent safely completing trial activities.
• Any individuals that weigh 275 lbs or more.
• Any individuals who wear their prosthesis less than 3 days a week or less than a total of 24 hours a week
• Individuals with a history of acute or chronic residual limb breakdown
• Individuals with declining health status such that he/she subsequently reports reduced activity over the past 6 months

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Prosthetic Limb Users Survey of Fall-Related Self-Efficacy (PLUS-F-SEF)	Collected at baseline, 1-month, 3-month, 6-month, 9-month, and 12-month assessments.	The PLUS-F-SEF is a 15-item self-report instrument we developed in the present study to measure perceived ability to avoid a loss of balance while performing an activity. Respondents rate their degree of confidence on a 5-point scale from "not at all confident" (1) to "very much confident" (5). A standardized T-score is generated for the PLUS-F-SEF using a lookup table that converts the raw score to a T-score.
Prosthetic Limb Users Survey of Fall-Related Anxiety (PLUS-F-ANX)	Collected at baseline, 1-month, 3-month, 6-month, 9-month, and 12-month assessments.	The PLUS-F-ANX is a 15-item self-report instrument we developed in the present study to measure perceived apprehensions or concerns about losing one's balance or falling. Respondents rate the frequency with which they experience various emotional responses on a 5-point scale from "never" (1) to "always" (5). A standardized T-score is generated for the PLUS-F-ANX using a lookup table that converts the raw score to a T-score.
Prosthetic Limb Users Survey of Fall-Related Avoidance Behaviors (PLUS-F-AVB)	Collected at baseline, 1-month, 3-month, 6-month, 9-month, and 12-month assessments.	The PLUS-F-AVB is a 15-item self-report instrument we developed in the present study to measure perceived changes in the manner or frequency with which activities are performed to avoid losing one's balance or falling. Respondents rate the frequency with which they make changes on a 5-point scale from "never" (1) to "always" (5). A standardized T-score is generated for the PLUS-F-AVB using a lookup table that converts the raw score to a T-score.
Prosthetic Limb Users Survey of Fall-Related Interference (PLUS-F-INT)	Collected at baseline, 1-month, 3-month, 6-month, 9-month, and 12-month assessments.	The PLUS-F-INT is a 15-item self-report instrument we developed in the present study to measure perceived restrictions in social, cognitive, emotional, and/or physical life situations due to risk of falls. Respondents rate the amount of interference on a 5-point scale from "not at all" (1) to "very much" (5). A standardized T-score is generated for the PLUS-F-INT using a lookup table that converts the raw score to a T-score.
Number of Reported Falls and Near-Fall Events	Collected every two weeks starting at baseline up to 12 months	Participants will be contacted every 2 weeks starting at baseline through study completion to determine whether they experienced a fall event (either a fall or near-fall). For each event experienced, participants will be asked to report the details of that event using the Lower Limb Prosthesis User Fall Event Survey we developed in a prior study. This instrument asks respondents to report the activity, surroundings, situation, mechanics, and consequences of each event. Fall events will be scored as the total number of falls, near-falls, and all fall events experienced. The details of the events are descriptive in nature and will be used to characterize the falls experienced by the participant.

Secondary Outcome Measures

Name	Time	Method
EuroQol 5 Dimensions (EQ-5D)	Collected at baseline, 6-month, and 12-month assessments.	The EQ-5D is a self-report measure of health-related quality of life (HRQL). The EQ-5D includes a descriptive component and a visual analog scale (VAS). The descriptive component evaluates respondents' HRQL in five areas (i.e., mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) using a five- or three-level response option. We will use the five-level response option (EQ-5D-5L) for this study, where level 1 indicates "no problem" and level 5 indicates "unable to/extreme problems." The VAS component measures the respondent's HRQL on a 0 (the worst imaginable health) to 100 (the best imaginable health) VAS scale.
Balance Recovery Scale (BRC)	Collected at baseline, 6-month, and 12-month assessments.	The BRC is a 19-item self-report questionnaire designed to measure balance recovery self-efficacy (i.e., perceived reactive balance recovery). Respondents rate the degree of confidence with which they can recover from different losses of balance on a 10-point scale, from "cannot do at all" (0) to "highly certain can do" (10). A summary score is generated from the responses to questions in the BRC.
Fear of Falling Avoidance Behaviors Questionnaire (FFABQ)	Collected at baseline, 6-month, and 12-month assessments.	The FFABQ is a 14-item self-report instrument that measures the degree to which respondents avoid activities due to their fear of falling. Respondents rate the amount of times they avoid select activities due to their fear of falling on a 5-point scale from "always (100% of the time)" to "never (0% of the time)." A summary score is generated from the responses to questions in the FFABQ.
Prosthetic Limb Users Survey of Mobility (PLUS-M)	Collected at baseline, 6-month, and 12-month assessments.	The PLUS-M is a 12-item self-report instrument we developed in a prior study to measure mobility with an LLP. Respondents rate their perceived difficulty with performing various household and community activities on a 5-point scale, ranging from "without any difficulty" (5) to "unable to do" (1). A standardized T-score is generated for the PLUS-M using a lookup table that converts the raw score to a T-score.
Timed Up and Go (TUG)	Collected at baseline, 6-month, and 12-month assessments.	The TUG is a performance-based test designed to measure basic mobility tasks, such as sit-to-stand, gait initiation, walking, turning, and stand-to-sit. The TUG requires the participant stand up from a standard chair with arms, walk at a comfortable speed for 3 meters, turn around, and return to sit in the chair. The administrator times the participant as they perform the test. Lower TUG times are indicative of better performance (mobility). The TUG is scored as the lowest time achieved in one of two timed trials.
Ten Meter Walk Test (10mWT)	Collected at baseline, 6-month, and 12-month assessments.	The 10mWT is a performance-based test designed to measure a participant's self-selected walking speed. The 10mWT requires the participant to walk at a normal speed between lines taped on the floor. The administrator measures the time required to walk the middle six meters of the 10-meter distance. Lower times (ie, faster speed) is indicative of better performance. The 10mWT is scored by calculating the participant's walking speed in meters per second (m/s).
Two Minute Walk Test (2MWT)	Collected at baseline, 6-month, and 12-month assessments.	The 2MWT is a performance test designed to measure submaximal walking endurance. The 2MWT requires the participant to walk as far as possible over a period of 2 minutes. Longer distances indicate better performance (i.e., greater endurance). The administrator measures the distance the participant travels during the test. The 2MWT is scored as the total distance traveled in meters (m) over the test period.

Trial Locations

Locations (1)

Hanger Inc.; 🇺🇸 Austin, Texas, United States