Socket-leg Interface Movements in Transtibial Amputees

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.

• Torque Required to Initiate Socket-Liner Rotation [Nm] [Срок оценки: Within 1 hour after fitting the suspension system]
• Step length [cm] [Срок оценки: Within 1 hour after fitting the suspension system]
• Step length asymmetry index [Срок оценки: Within 1 hour after fitting the suspension system]
• Gait velocity [m/s] [Срок оценки: Within 1 hour after fitting the suspension system]
• Patient-Reported Socket Comfort Score (SCS) [Срок оценки: Within 1 hour after fitting the suspension system]
• Perceived Functional Ability [Срок оценки: Within 1 hour after fitting the suspension system]
• Prosthesis Satisfaction Score [Срок оценки: Within 1 hour after fitting the suspension system]