Santosh Zachariah, Ph.D.
Department of Bioengineering, Prosthetic Engineering Lab
"Shape, Interface Mechanics, and Things to come"
ABSTRACT
A lower-limb prosthesis (artificial leg) must satisfy three
requirements: It must look right; It must restore, at least
partially, the lost function of the foot, ankle, and (possibly) knee
joint; And it must transfer force from the skeleton to the
ground, *without* causing pain or injury to the tissues. It is
this last requirement that interests us at the Prosthetic Engineering
Laboratory, in the Dept. of Bioengineering.
At present, the soft tissues of the amputated limb are between a rock
and a hard place. On one side is the bone, to or from which force
has to be transferred. On the other side is the prosthetic
socket, which must be durable enough to withstand the applied loads and
provide stability. External force from the base of the socket
flows as interface stress between the socket and the skin, and then as
internal stresses within the soft tissues to the bone.
The interface stresses - the ones that cause most pain and damage - can
be visualized as pressure (a normal stress) and shear (a tangential
stress governed by friction. In my talk, I will discuss how we
try and understand these stresses - by measurement and modeling.
I will elaborate on why we focus on shape as the one of the most
significant parameters modulating interface stresses. And
finally, I will introduce the concept of a shape adaptable socket.