Transtibial Amputation - Unilateral
Conditions
Keywords
Transtibial amputation, Lower-limb prosthesis, Prosthetic socket fit, 3D motion capture, Prosthesis comfort, Prosthetic rotation resistance, Pistoning, Prosthetic suspension systems, Prosthetic alignment, gait
Brief 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. 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.
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.
Interventions
DEVICEPin-Lock Suspension System
Participants perform all tasks using a pin-lock suspension system applied to their test socket.
DEVICEPassive Vacuum Suspension System
Participants perform all tasks using a passive vacuum suspension system applied to their test socket.
DEVICEActive Vacuum Suspension System
Participants perform all tasks using an active vacuum suspension system applied to their test socket.
Sponsors
Norwegian University of Science and Technology
Trøndelag Ortopediske Verksted (English translation: Trøndelag Orthopedic Workshop)
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
OTHER
Masking
NONE
Intervention 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.
Eligibility
Sex/Gender
ALL
Age
16 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* 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)
Exclusion criteria
* 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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Socket-Liner Motion [mm] | Within 1 hour after fitting the suspension system | 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. |
| Proximal-distal Socket-Leg Motion [mm] | Within 1 hour after fitting the suspension system | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Torque Required to Initiate Socket-Liner Rotation [Nm] | Within 1 hour after fitting the suspension system | 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. |
| Step length [cm] | Within 1 hour after fitting the suspension system | Step length is quantified using a 3D motion-capture system during functional activities. Step length is recorded in centimeters (cm). |
| Step length asymmetry index | Within 1 hour after fitting the suspension system | 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. |
| Gait velocity [m/s] | Within 1 hour after fitting the suspension system | Gait velocity is quantified using a 3D motion-capture system during functional activities. Gait velocity is recorded in meters per second (m/s). |
| Patient-Reported Socket Comfort Score (SCS) | Within 1 hour after fitting the suspension system | 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. |
| Perceived Functional Ability | Within 1 hour after fitting the suspension system | 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. |
| Prosthesis Satisfaction Score | Within 1 hour after fitting the suspension system | 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. |
Countries
Norway
Contacts
CONTACTKarin Roeleveld, PhD
CONTACTMaria J Lequerica, MSc
PRINCIPAL_INVESTIGATORKarin Roeleveld
National Taiwan Normal University
Outcome results
None listed