The project investigates how movements between the prosthetic socket and the residual limb—called socket-leg interface movements (SLMs)—can be used to assess and improve prosthetic fit for transtibial amputees.

A well-fitting prosthesis is essential for comfort, mobility, and quality of life. Yet, many users experience discomfort and require frequent adjustments. This project aims to further develop objective, dynamic methods (using motion capture technology) to assess prosthetic fit.
 

1.    Suspension Systems

• Does the suspension system in use (pin lock, passive vacuum, active vacuum) have an effect on the SLM?

2.     Torque Resistance Capacity

• How much rotational force (torque) can the prosthesis system withstand before rotational motion occurs between the socket and the liner?
• Does this resistance depend on the suspension system used?
• Is it affected by proximal-distal loads and displacements?

3.    Rotation-Inducing Activities and Socket-Leg Motion

• How do rotation-inducing activities (e.g., pivoting, turning) affect socket-leg interface movements in transtibial prosthesis users?
• Do different suspension systems influence the degree of socket-leg motion during these activities?
• Is reduced socket-leg motion associated with improved functional performance?

4.    Walking Velocity and Gait

• How does walking speed (e.g., preferred vs. fast) affect socket-leg interface motion in transtibial prosthesis users?
• Do different suspension systems respond differently to changes in walking velocity?
• Is gait symmetry or stability influenced by socket-leg motion?

5.     Patient-Reported Outcomes and Socket-Leg Motion

• What is the relationship between socket-leg interface motion and patient-reported outcomes such as comfort, satisfaction, and perceived functionality?
• Do users reporting higher comfort and satisfaction experience less socket-leg motion during dynamic tasks?
• Can PROMs be used to predict or validate objective measures of prosthetic fit?

Participants with transtibial amputations will take part in a series of dynamic tasks using three different suspension systems: pin lock, passive vacuum, and active vacuum.

Each participant will complete the full sequence of tests with all three systems, allowing for repeated measures and comparison across conditions.

For each suspension system, participants will perform:

• Biodex Tasks: Assessing torque resistance at the socket-leg interface
• Treadmill Tasks: Evaluating socket-leg motion while walking at self-selected preferred walking speed and self-selected fastest walking speed
• Rotational Tasks: Measuring motion during turning and curved walking on level ground

These tasks are designed to capture how each suspension system influences socket-leg motion, gait performance, and user comfort. Motion is recorded using a 3D motion capture system, and outcomes are supported by gait metrics and questionnaires.

1. Provide clinicians with objective tools to assess prosthetic fit
2. Improve prosthetic design and fitting protocols
3. Enhance user comfort and mobility
4. Reduce healthcare costs by minimizing socket refittings