Using a Simple Walking Model to Optimize Transfemoral Prostheses for Prosthetic Limb Stability-A Preliminary Study

Area of Science:

• Biomechanics
• Prosthetics
• Gait Analysis

Background:

• Safe transfemoral prosthesis use relies on prosthetic knee-foot interaction during gait's stance phase.
• Knee buckling during stance can lead to falls, highlighting the need for standardized assessment methods.
• Current methods lack standardization for quantifying prosthetic component interactions and their biomechanical effects.

Purpose of the Study:

• To develop a numerical model for simulating prosthetic limb stance and predicting component interaction effects.
• To identify optimal combinations of prosthetic knee alignment and foot stiffness for user safety.
• To provide clinicians with data-driven insights for optimizing transfemoral prosthesis design.

Main Methods:

• A numerical model simulating sagittal plane prosthetic limb stance using a single inverted pendulum.
• Prediction of knee moment based on prosthetic knee alignment and foot stiffness (roll-over shape radius).
• Model validation against laboratory gait data for single-limb support scenarios (knee flexion < 4°).

Main Results:

• A solution space was identified for stable prosthetic knee function during early and mid-stance.
• Optimal combinations involve posterior to in-line knee alignment with low-to-medium ankle-foot stiffness.
• Anterior knee alignments and rigid prosthetic feet are predicted to increase instability risks.

Conclusions:

• The model provides a tool to optimize transfemoral prostheses, enhancing user safety by preventing knee buckling.
• Findings guide clinical practice by defining safe parameter spaces for knee alignment and foot stiffness.
• Results can inform future research and clinical guidelines for prosthetic device design and application.