NCT07521891

Socket-leg Interface Movements in Transtibial Amputees

Socket-leg Interface Movements as a Measure of Dynamic Prosthetic Fit for Transtibial Amputees: An Exploratory Study

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 20 (estimated)
• Sponsor: Norwegian University of Science and Technology · Academic / Other
• Sex: All
• Age: 16 Years
• Healthy volunteers: Not accepted

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.

Conditions

• Transtibial Amputation - Unilateral

Interventions

Type	Name	Description
DEVICE	Pin-Lock Suspension System	Participants perform all tasks using a pin-lock suspension system applied to their test socket.
DEVICE	Passive Vacuum Suspension System	Participants perform all tasks using a passive vacuum suspension system applied to their test socket.
DEVICE	Active Vacuum Suspension System	Participants perform all tasks using an active vacuum suspension system applied to their test socket.

Timeline

• Start date: 2026-04-20
• Primary completion: 2027-02-27
• Completion: 2029-12-27
• First posted: 2026-04-13
• Last updated: 2026-04-13

Locations

1 site across 1 country: Norway