experience prosthetic socket discomfort.
It’s both a technology problem and it’s a science problem
because we don’t really know
how to connect the body to machines.
( applause )
There are ten million people
living with amputations globally.
They could have gotten those from accidents
victims of war
or diabetes.
They range from people who are in the US
to people who are in my home in Sierra Leone
to Cambodia, all over the world.
But one thing is constant.
Hundred percent of them
experience prosthetic socket discomfort.
That’s a residual limb with bones inside.
That is very different for everybody.
The part that connects
that residual limb to the prosthetic leg is uncomfortable.
And part of that is because
the way we conventionally make prosthetic sockets today
is through an artisanal process for an ever changing human body
that is so diverse across the population
and across the whole world.
And the way prosthesis
prosthetic sockets are designed today
is you go to a prosthetist and they take your leg
and they squeeze your leg and ask you, “How does that feel
if I press here a little bit does it feel great?
What about that, what about your patellar tendon?
What about this bone that’s there
is there a bone in there I don’t know?
How did this happen?” You get the picture.
It is not repeatable.
It is based on the experience of the prosthetist.
And the mold that is created is based on somebody’s experience.
You create and alter that positive mold
you make a negative mold
and then you pour another positive mold inside
and then you modify that, and then you make a test socket
and then the person goes into the test socket
they give you feedback, like telling
“Oh, I don’t think it’s comfortable here”
and then you modify it again
and then you do this over and over and again.
Until you or the person goes
“Yeah, it’s fine, I can work in this”.
( audience laughter )
And when you do get carbon fiber sockets of single material
you have your residuum get blisters and pressure sores.
If you look closely around the fibular head there
you can see some blood spots.
It’s both a technology problem and it’s a science problem
because we don’t really know how to connect the body to machines.
So, one of the things that I was interested in with my boss was
how do you understand the science
behind designing for comfort.
So, on the left is a fit-socket, which is an array of indentors
in which the person inserts their residuum
to capture experimental data of force, displacement and time
so we can use it to characterize the model of the person’s body.
I decided that it was perhaps useful to
link those points with a MRI, so that we can
create models and we can link the experimental data
to the modeling data directly.
So, we have these markers that you can see in an MRI
and you segment that MRI, so we define the bones
define the skin, define all the other soft tissue.
And then we can create in an exact replica, so we can
ask questions around design of the interfaces we have.
And then we can build models that is predictive,
and we can use these to now say what happens inside the body.
How is the soft tissue straining around the bone.
We can test all of these now and go in and say
“Well, we don’t need to make a single material socket anymore.
We can now take your body with all those markers that we put
and that model that we created
that was validated and that’s predictive
create an element all across your body
with which we create the sockets
where each color is a new material
and test this hypothesis.
Why does this all matter?
Why… why does understanding the science of
how we connect the body to machines matter?
Your shoes still give you blisters.
If you know somebody who has scoliosis
they hate wearing their brace.
If you have a knee or an ankle injury, you hate your braces.
And that’s because we don’t know
how to connect the body comfortably to machines.
And, the science behind designing for comfort
really starts from being able to
merge these experimental and numerical data
and build predictive models, and ask questions around
how our design actually affects the behavior of the body
as we use these machines in time
and across loads and across different terrains.
”
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