Effect of a Microprocessor-controlled Prosthetic Knee Joint on K2 Level Ambulators (MPK-K2)

Does a Microprocessor-Controlled Prosthetic Knee Joint Improve Mobility and Quality of Life in K2-Level Veteran Ambulators?

Microprocessor-controlled knees (MPKs) automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the prosthesis user during gait. The purpose of this proposed investigation is to determine if there are substantial physical and psychological benefits to fitting lower functioning Veteran ambulators having transfemoral amputations with an MPK compared with a nonmicroprocessor-controlled knee (NMPK). Using a repeated-measures, cross-sectional experimental design, approximately 20 Veterans with unilateral, transfemoral amputations will be evaluated on two separate occasions at the Jesse Brown VA Medical Center or the Edward Hines, Jr. VA Hospital, first with their conventional NMPK and then again after a 2-month accommodation period with the College Park Icon MPK.

Study Overview

• Status: Not yet recruiting
• Conditions: Transfemoral Amputation; Limb Loss; Limb Absence
• Intervention / Treatment: Other: College Park ICON; Other: Conventional NMPK

Detailed Description

Limb loss is a potentially devastating event in a person's life, often resulting in profound physical, psychological, and vocational consequences. A transfemoral amputation results in greater physical and functional impairment and an increased risk of falling in patients as compared to someone with a transtibial amputation. Furthermore, balance confidence and fear of falling appears to be a persistent and pervasive problem among lower-limb prosthesis users, which adversely affects mobility and quality of life. During the past 30 years there have been several major developments in prosthetic knee mechanisms that incorporate microprocessors to improve swing-phase characteristics and provide greater stability during stance phase. Microprocessor-controlled knees (MPKs) automatically adjust resistance or damping in the joint to improve swing- and/or stance-phase control as appropriate for the user during gait.

There are numerous reported benefits of MPKs over non-microprocessor controlled knees (NMPKs), including faster self-selected walking speeds, reduced cognitive burden while walking, fewer stumbles and falls, and increased perceptions of confidence and safety while ambulating. Nonetheless, MPKs are not typically prescribed or fitted on lower functioning ambulators, which is the activity classification of most Veteran patients.

The purpose of this proposed investigation is to determine if there are substantial physical and psychological benefits to fitting lower functioning Veteran ambulators having transfemoral amputations with an MPK compared with a NMPK. The specific aims and hypotheses of this project are:

Aim 1: To determine the effects of the College Park Icon on the mobility of unilateral, transfemoral prosthesis users. The investigators hypothesize that the MPK will enable users to 1) increase their freely-selected (i.e., normal) walking speed, and 2) walk over a wider range of speeds. Furthermore, the investigators hypothesize that 3) participants will report fewer falls with the MPK.

Aim 2: To determine the effects of the College Park Icon on the psychological well-being of unilateral, transfemoral prosthesis users. The investigators hypothesize that subjects will improve their scores on patient-reported outcome assessments including the ABC, OPUS, and PLUS-M with the MPK.

Aim 3: To determine subjects' preference for the College Park Icon compared to their conventional NMPK. At the completion of the study, the investigators will ask participants which prosthetic knee type they preferred. It's hypothesized that the majority of participants will prefer using the MPK over the NMPK. Those subjects who prefer the MPK will be permitted to keep the component in their prosthesis, while those who prefer their NMPK will have their prosthesis returned to its original configuration.

Using a cross-sectional experimental design, approximately 20 Veterans who are low functioning ambulators with unilateral, transfemoral amputations will be evaluated on two separate occasions at the Jesse Brown VA Medical Center or the Edward Hines, Jr. VA Hospital, first with their conventional NMPK and then again after a two-month accommodation period with the College Park Icon MPK.

This work is directly applicable to VHA's Patient Care Mission because the results may justify the fitting of MPKs on low-level ambulators within the VA system and substantially improve the mobility of Veterans with lower limb amputations while increasing their quality of life.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rebecca Stine, MS; Phone Number: (312) 503-5726; Email: rebecca.stine@va.gov
• Study Contact Backup: Name: Steven A Gard, PhD; Phone Number: (312) 503-5718; Email: steven.gard@va.gov

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60612
      • Jesse Brown VA Medical Center, Chicago, IL
      • Contact: Rebecca Stine, MS; Phone Number: 312-503-5726; Email: rebecca.stine@va.gov
      • Principal Investigator: Steven A Gard, PhD
      • Contact: Steven A Gard, PhD; Phone Number: (312) 503-5718; Email: steven.gard@va.gov
    • Hines, Illinois, United States, 60141-3030
      • Edward Hines Jr. VA Hospital, Hines, IL
      • Contact: Rebecca Stine, MS; Phone Number: 312-503-5726; Email: rebecca.stine@va.gov
      • Contact: Steven A Gard, PhD; Phone Number: 3125035718; Email: steven.gard@va.gov

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Unilateral, transfemoral amputation (any etiology).
• Age from 45-85 years.
• Residual limb length classified as standard (i.e., medium) to long.
• Prosthesis user for at least 1 year prior to enrolling in the study.
• K2-level classification while using their NMPK.
• Good sensation on their residual limb.
• Good skin integrity upon visual inspection.
• Presents with good socket fit based upon a standard assessment by the study prosthetist.

Exclusion Criteria:

• Bilateral leg amputations.
• Individuals with a knee disarticulation.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: MPK; Subjects will be fitted with the College Park ICON MPK and permitted to accommodate for 2 months prior to data collection.	Other: College Park ICON; Subjects will be fitted and trained on the College Park ICON MPK. An accommodation period of 2 months will be provided prior to evaluation with the knee joint.
Active Comparator: NMPK; Subjects will initially be evaluated walking on their conventional NMPK as a baseline prior to being fitted with the MPK.	Other: Conventional NMPK; Subjects will be tested walking with their conventional, mechanical prosthetic knee prior to being fitted with the MPK.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Walking speed	Walking speed will be measured as participants walk on level ground at slow, normal and fast speeds.	To be measured before and immediately following the 2-month accommodation period of wearing the MPK.
Falls during walking	The number of falls that occur while the subject is walking will be recorded in a daily diary.	To be determined before and during the 2-month accommodation period of wearing the MPK
PLUS-M	The Prosthetic Limb User Survey of Mobility (PLUS-M) will be used to determine the mobility of subjects before and after fitting with the MPK. Scores range from 12-60 points, and a higher score indicates greater mobility.	To be measured before and immediately following the 2-month accommodation period of wearing the MPK.
Prosthetic Knee Preference	Subjects will be asked which prosthetic knee they prefer at the completion of the study. For those that indicate preference for the MPK, they will be permitted to keep it in their prosthesis. For those that prefer the NMPK, their prosthesis will be restored to the configuration prior to beginning the study.	To be asked immediately following the 2-month accommodation period of wearing the MPK.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
ABC Scale	The Activities-specific Balance Confidence (ABC) Scale measures the subject's confidence in not losing their balance or becoming unsteady while performing different activities. Scores range from 0-100%, where zero represents no confidence and 100 represents complete confidence in performing an activity without losing balance or becoming unsteady.	To be administered before and immediately following the 2-month accommodation period of wearing the MPK.
OPUS	The Orthotics and Prosthetics User's Survey (OPUS) is a self-report questionnaire that can be used 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. Scores range from 0-80 points, with a higher score indicating greater functional mobility.	To be administered before and immediately following the 2-month accommodation period of wearing the MPK.

Collaborators and Investigators

• Sponsor: VA Office of Research and Development
• Investigators: Principal Investigator: Steven A Gard, PhD, Jesse Brown VA Medical Center, Chicago, IL

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): May 1, 2028
• Study Completion (Estimated): June 30, 2028

Study Registration Dates

• First Submitted: July 15, 2025
• First Submitted That Met QC Criteria: July 31, 2025
• First Posted (Actual): August 5, 2025

Study Record Updates

• Last Update Posted (Actual): May 8, 2026
• Last Update Submitted That Met QC Criteria: May 7, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: prosthesis; amputation; limb deficiency; limb loss; knee joint; transfemoral; above-knee
• Other Study ID Numbers: RRD2-005-24W; RX005610 (Other Grant/Funding Number: VA RRD)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: A Limited Dataset (LDS) will be created and shared pursuant to a Data Use Agreement (DUA) appropriately limiting use of the dataset and prohibiting the recipient from identifying or re-identifying (or taking steps to identify or re-identify) any individual whose data are included in the dataset. Results from this study will be freely disseminated via presentations at professional conferences and publications in scientific journals. Additionally, data acquired for this project will be shared with those investigators who make a formal request to the PI and can demonstrate a legitimate and justifiable cause for utilization of such data. All requests for these data will be discussed with the VA scientific program manager.

Drug and device information, study documents

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