Transtibial Amputation - UnilateralSLMinTTANCT07521891
Socket-leg Interface Movements in Transtibial Amputees
A study testing Pin-Lock Suspension System, Passive Vacuum Suspension System and Active Vacuum Suspension System in people with Transtibial Amputation - Unilateral, run by Norwegian University of Science and Technology at 1 site in Norway.
Trial summary
This exploratory interventional study investigates dynamic prosthetic fit in unilateral transtibial prosthesis users by objectively measuring socket-leg interface movements (SLMs) during functional activities. Read more about this study
- Who is it for?
- Ages 16 years and older
- Conditions the study is for
- Transtibial Amputation - Unilateral
- What is being tested?
- Pin-Lock Suspension System, Passive Vacuum Suspension System and Active Vacuum Suspension System
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteNorway
- Study dates
- 20 Apr 2026to 27 Dec 2029
- Phase
- Interventional
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 16 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Age ≥16 years
- Unilateral transtibial amputation
- Activity level K2-K4
- Actively using a prosthesis for ≥12 months
- Ability to understand and communicate in Norwegian (oral and written)
- Digital file of current socket model available (required for test socket fabrication)
Who cannot join
- Use of a thigh corset attached to the prosthesis
- Requirement of a walker for ambulation
- Open wounds, skin ulcers, or blisters on the residual limb
- No liner
- Missing digital socket model file
- Medical advice to avoid physical activity similar to study tasks
- Other medical conditions that may worsen with activity and have not been cleared by a healthcare professional
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Norway1 site
NTNU's Movement analysis laboratory at Helgasetr
Trondheim, 7030
Maria J Lequerica, MSc - PhD candidate, +47 48684299, maria.j.lequerica@ntnu.no
Karin Roeleveld, PhD, +47 48177279, karin.roeleveld@ntnu.no
About this study
Official title: Socket-leg Interface Movements as a Measure of Dynamic Prosthetic Fit for Transtibial Amputees: An Exploratory Study
This exploratory interventional study investigates dynamic prosthetic fit in unilateral transtibial prosthesis users by objectively measuring socket-leg interface movements (SLMs) during functional activities. During one single study visit, participants complete standardized laboratory tasks using three different suspension systems (pin-lock, passive vacuum, and active vacuum) applied to a transparent replica of their current prosthetic socket. Motion capture, force measurements, and patient-reported outcomes are used to evaluate how suspension systems influence interface motion, rotation resistance, gait characteristics, and user comfort. The study aims to improve clinical understanding of prosthetic fit and support more informed prosthetic decision-making in routine care.
Read the detailed description
Transtibial prosthetic fit strongly influences user comfort, gait quality, and long term functional outcomes. Current clinical assessment methods rely primarily on subjective clinical observation and user feedback. Dynamic socket-leg interface motion (SLM) offers an objective biomechanical indicator of prosthetic fit, but existing studies are limited in sample size, measurement directions, and evaluation across different suspension systems.
This study evaluates SLMs using 3D motion capture, force sensors, and a dynamometer while participants perform three standardized task categories:
isometric rotation tasks to determine rotation resistance and torque thresholds for interface rotation; turning/rotational/pivoting walking tasks to assess functional performance and transverse plane dynamics; and treadmill walking at multiple speeds to quantify proximal-distal pistoning and gait kinematics.
Each participant is tested using three suspension system conditions (pin-lock, passive vacuum, active vacuum), starting with their preferred suspension system followed by a counterbalanced order to minimize bias. A transparent "test socket" replicating the participant's own socket allows interface visualization and marker tracking without altering the intended use of the prosthesis. The investigational device consists only of CE marked components used within their intended purpose.
Participants attend one study visit with a duration of approximately 4 to 5 hours, including prosthesis adjustment and placement, marker setup, data collection across all three task categories and with all three suspension system conditions.
The primary aim is to quantify the effects of suspension system and load conditions on SLMs and gait performance. Secondary aims assess relationships between objective SLM measures and patient reported comfort, functional ability with the prosthesis, and prosthesis satisfaction. Findings will support improved understanding of dynamic fit behavior, help characterize suspension system performance, and inform future development of objective prosthetic fitting assessment methods.
- Conditions
- Transtibial Amputation - Unilateral
- Being tested
- Pin-Lock Suspension System, Passive Vacuum Suspension System, Active Vacuum Suspension System
- Keywords
- Transtibial amputation, Lower-limb prosthesis, Prosthetic socket fit, 3D motion capture, Prosthesis comfort, Prosthetic rotation resistance, Pistoning, Prosthetic suspension systems, Prosthetic alignment, gait
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Pin-Lock Suspension SystemDevice
Participants perform all tasks using a pin-lock suspension system applied to their test socket.
Passive Vacuum Suspension SystemDevice
Participants perform all tasks using a passive vacuum suspension system applied to their test socket.
Active Vacuum Suspension SystemDevice
Participants perform all tasks using an active vacuum suspension system applied to their test socket.
| Study group | Role | What they receive |
|---|---|---|
| Single Cohort: Three Suspension Systems | Experimental | Participants with unilateral transtibial amputation will attend one study visit at the research site. During this visit, they will complete three movement tasks-treadmill walking, overground turning, and isometric leg rotation-while using three different prosthetic suspension systems in a partly randomized order (pin lock, passive vacuum, and active vacuum). Each of the three movement tasks will be performed with each of the three suspension systems. Biomechanical, performance, and patient-reported outcomes will be recorded for each suspension condition. Receives: Device: Pin-Lock Suspension System; Device: Passive Vacuum Suspension System; Device: Active Vacuum Suspension System |
What is being measured
The primary outcome is the main question the study is designed to answer.
Socket-Liner Motion [mm]
Socket-liner motion is quantified using a 3D optical motion-capture system to measure the relative movement between the prosthetic socket and liner during functional activities. Motion is recorded in millimeters (mm).
Typical motion values are expected to fall within the range of 0-20 mm.
Measured: Within 1 hour after fitting the suspension system
Proximal-distal Socket-Leg Motion [mm]
Proximal-distal Socket-Leg Motion is quantified using a 3D motion-capture system to measure the relative movement between the prosthetic socket and the remaining leg during functional activities. Motion is recorded in millimeters (mm).
Typical motion values are expected to fall within the range of 0-30 mm.
Measured: Within 1 hour after fitting the suspension system
Secondary outcomes (7)
Torque Required to Initiate Socket-Liner Rotation [Nm]
This measure quantifies the torque at which transverse rotation begins between the prosthetic socket and liner. Torque is measured in Newton-meters (Nm) using a dynamometer.
Measured: Within 1 hour after fitting the suspension system
Step length [cm]
Step length is quantified using a 3D motion-capture system during functional activities. Step length is recorded in centimeters (cm).
Measured: Within 1 hour after fitting the suspension system
Step length asymmetry index
Step length asymmetry will be assessed using 3D motion analysis instrumentation. Asymmetry is computed on step length (cm) of the prosthetic and intact legs, by dividing the difference between legs by the average of both legs. 0 marks perfect symmetry and greater values higher asymmetry. There is no maximum limit, but most values are expected to be below 1.
Measured: Within 1 hour after fitting the suspension system
Gait velocity [m/s]
Gait velocity is quantified using a 3D motion-capture system during functional activities. Gait velocity is recorded in meters per second (m/s).
Measured: Within 1 hour after fitting the suspension system
Patient-Reported Socket Comfort Score (SCS)
The Socket Comfort Score is a patient-reported numerical rating scale used to assess prosthetic socket comfort. Participants rate their comfort on a 0-10 scale, where 0 represents the most uncomfortable socket imaginable and 10 represents the most comfortable socket imaginable.
Comfort is evaluated for each of the three suspension conditions. For every condition, the participant provides the score immediately after completing the turning task and treadmill-walking task, both performed within 60 minutes of fitting the corresponding suspension system.
Measured: Within 1 hour after fitting the suspension system
Perceived Functional Ability
Perceived functional ability is assessed using a patient-reported numerical rating scale that captures the participant's subjective evaluation of how well they are able to perform functional activities with the prosthesis. Participants rate their perceived functional ability on a 0-10 scale, where 0 indicates the lowest perceived functional ability and 10 indicates the highest perceived functional ability.
For each of the three suspension conditions, participants provide this rating immediately after completing the turning task and treadmill-walking task, both performed within 60 minutes of fitting the respective suspension system.
Measured: Within 1 hour after fitting the suspension system
Prosthesis Satisfaction Score
The Prosthesis Satisfaction Score is a patient-reported numerical rating scale used to assess overall satisfaction with the prosthetic limb. Participants rate their satisfaction on a 0-10 scale, where 0 represents the lowest possible satisfaction and 10 represents the highest possible satisfaction.
For each of the three suspension conditions, participants provide this rating immediately after completing the turning task and treadmill-walking task, both performed within 60 minutes of fitting the corresponding suspension system.
Measured: Within 1 hour after fitting the suspension system
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Apr 2026
- Study start20 Apr 2026 (estimated)
- Primary completion27 Feb 2027 (estimated)
- Study completion27 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Transtibial Amputation - UnilateralStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- All participants complete the same set of laboratory tasks under three suspension system conditions (pin-lock, passive vacuum, active vacuum). The sequence of conditions is partly determined by the participant's current or preferred suspension system, which is always tested first, and partly counterbalanced for the remaining two suspension systems to reduce order effects. Each participant serves as their own control.
- Masking
- None (open label)
- Enrolment
- 20 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Norwegian University of Science and Technology
- Sponsor type
- University, hospital or other
- Collaborators
- Trøndelag Ortopediske Verksted (English translation: Trøndelag Orthopedic Workshop)
- Responsible party
- Sponsor
- Investigators
- Karin Roeleveld, Principal investigator, National Taiwan Normal University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07521891
- Sponsor's protocol ID
- 938884
- Acronym
- SLMinTTA
- Status last verified
- Apr 2026
- First submitted
- 5 Mar 2026
- Last updated
- 13 Apr 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data (IPD) from this study cannot be shared because the data are not anonymous. According to REK regulations and GDPR requirements, the research team must retain the identification key for as long as the data are used for research purposes. As long as this key exists, the dataset is considered identifiable, and sharing identifiable or potentially re-identifiable data externally is not permitted. Therefore, IPD cannot be shared.