William Ledoux, Ph.D.
VA Center of Excellence for Limb Loss Prevention and Prosthetic Engineering
E-mail: wrledoux@uw...


TITLE:

"New Techniques for Quantifying Foot Biomechanics"


ABSTRACT:

  The work of our group is aimed at preventing functional and/or anatomical limb loss.
Functional limb loss refers to lower extremities that no longer work properly, frequently due
to ankle osteoarthritis or muscle imbalance induced deformity. Anatomical limb loss results
from amputation, often due to complications arising from diabetes.

 Over the last decade, we have developed numerous techniques for studying the disease processes
that can lead to limb loss. These include the robotic gait simulator (RGS) where we move the
?ground? relative to a fixed cadaveric foot, matching tibial kinematics and ground reaction
forces for a target population. Outputs include foot bone kinematics and plantar pressure
distribution, and can be compared pre- and post-treatment. We have also developed a biplane
fluoroscope -- a synchronized dual X-ray machine that, when combined with a computed tomography
(CT) scan of the foot, allows for tracking of individual foot bones during stance.

 Related to diabetes, our approach has been two fold. We have done extensive testing on
diabetic and non-diabetic cadaveric tissues, demonstrating mechanical differences in
compressive and shear stiffness, and histological differences in the fat pad septal wall
thickness. Additionally, we have developed a magnetic resonance (MR)-compatible loading device
for gated-MR scanning of diabetic and non-diabetic feet. When combined with a patient-specific
finite element model and the inverse finite element method, this loading device can be used to
generate patient-specific material properties. Together, these techniques have provided our
research group with a strong foundation to begin to address many limb loss prevention treatment
strategies.