Pivot-Flex Foot: Optimal Coupling Ratio Between Transverse and Sagittal-plane Motions Using a Torsionally Adaptive Prosthesis for Individuals With Lower Limb Amputation
Pivot-Flex Foot: Torsionally Adaptive Prosthesis for Individuals With Lower Limb Amputation
3 other identifiers
interventional
14
1 country
1
Brief Summary
When prescribing a prosthetic foot, clinicians face a dizzying array of choices as more than 200 different prosthetic feet are available. While these conventional prosthetic feet primarily function in the sagittal plane, the intact foot and ankle comprise a complex set of joints that allow rotation in multiple planes of motion. Some of these motions are coupled, meaning rotation in one plane induces motion in another. One such coupling is between the sagittal and transverse planes. For every step, plantar- and dorsi-flexion motion in the sagittal plane is coupled with external and internal rotation of the shank relative to the foot in the transverse plane. There is no prosthetic foot available for prescription that mimics this natural coupling. To investigate the need for this coupling, the investigators have built a torsionally adaptive prosthesis where the coupling ratio between the transverse- and sagittal-planes can be independently controlled with a motor. This research has one specific aim: to identify the optimal coupling ratio between transverse- and sagittal-plane motions using a novel, torsionally adaptive prosthesis for individuals with lower limb amputation. The investigators will conduct a human subject experiment wearing the motor-driven and computer controlled torsionally adaptive prosthesis. Individuals with lower limb amputation will be asked to walk in a straight line and in both directions around a circle while the coupling ratio between transverse- and sagittal-plane motions is varied between trials. Participants will be blinded to the coupling ratio. The investigators hypothesize that: (1) a coupling ratio exists that minimizes undesirable transverse-plane socket torque and (2) there will be a coupling ratio that individuals with lower limb amputation prefer.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at below P25 for not_applicable
Started Apr 2018
Longer than P75 for not_applicable
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
Study Start
First participant enrolled
April 18, 2018
CompletedFirst Submitted
Initial submission to the registry
May 9, 2018
CompletedFirst Posted
Study publicly available on registry
May 22, 2018
CompletedPrimary Completion
Last participant's last visit for primary outcome
October 1, 2024
CompletedStudy Completion
Last participant's last visit for all outcomes
November 18, 2024
CompletedResults Posted
Study results publicly available
November 19, 2025
CompletedNovember 19, 2025
November 1, 2025
6.5 years
May 9, 2018
September 24, 2025
November 5, 2025
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Peak Transverse-plane Prosthetic Socket Torque Normalized to Body Mass
Peak transverse-plane prosthetic socket torque measured while walking normalized to body mass
During walking trials for each coupling ratio
Secondary Outcomes (1)
Satisfaction With the Prosthesis
Immediately following walking trials for each coupling ratio
Study Arms (3)
Straight line walking
EXPERIMENTALAll participants will walk in a straight line while wearing the study prosthesis.
Circle walking with prosthesis inside
EXPERIMENTALAll participants will walk around a 1-meter radius circle with their prosthesis on the inside of the circle.
Circle walking with prosthesis outside
EXPERIMENTALAll participants will walk around a 1-meter radius circle with their prosthesis on the outside of the circle.
Interventions
The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
Eligibility Criteria
You may qualify if:
- Unilateral transtibial amputation
- Been fit with a prosthesis and used it for at least six months
- Wear the prosthesis for four or more hours on an average day
- Prescribed prosthesis can accommodate fitment of the study prosthetic components to be tested (determined at initial visit)
You may not qualify if:
- Improper fit and suspension with current prosthesis and one cannot be achieved with clinical resources (determined at initial visit)
- Current skin irritation or injury on residual limb
- Osteoarthritis, injury, or pain that interferes with walking ability
- Currently incarcerated
- Pregnant (determined via self-report)
- Inadequate cognitive function or language proficiency to consent to participate
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
VA Puget Sound Health Care System Seattle Division, Seattle, WA
Seattle, Washington, 98108-1532, United States
Results Point of Contact
- Title
- Glenn Klute, PhD
- Organization
- CLiMB
Study Officials
- PRINCIPAL INVESTIGATOR
Glenn K Klute, PhD
VA Puget Sound Health Care System Seattle Division, Seattle, WA
Publication Agreements
- PI is Sponsor Employee
- Yes
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- NONE
- Purpose
- TREATMENT
- Intervention Model
- FACTORIAL
- Sponsor Type
- FED
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
May 9, 2018
First Posted
May 22, 2018
Study Start
April 18, 2018
Primary Completion
October 1, 2024
Study Completion
November 18, 2024
Last Updated
November 19, 2025
Results First Posted
November 19, 2025
Record last verified: 2025-11
Data Sharing
- IPD Sharing
- Will share
- Time Frame
- Within six months after publication of final study findings.
- Access Criteria
- Open access through PubMed Central, SimTK, PhysioNet, or other similar open-source data repository websites. The investigators will work with manuscript publishers when possible to link the final study data sets to an appendix of supplemental materials on the publisher websites.
A de-identified, anonymized dataset in machine-readable format will be created and shared for all individual participant data (IPD) that underlie results in a publication. The investigators will follow 164.514(a) of the HIPAA Privacy Rule for de-identification of IPD.