Our next.

Our next speaker mentioned is Childers

he is a doctoral student at you know

he's a doctoral in our doctoral program
and Lee has the better science and

mechanical engineering and
he also is an M.S.P.

Georgia Tech graduate and so
shortly after his after you graduate.

He's are again as mentioned our
first Ph D. program student.

And we thank you

thank you very much the case of Leonard
auction and thank you everyone for coming.

It's a great pleasure to get to talk to
everyone and try to disseminate what we've

been learning here out into the clinical
practice or at least clinical field and

what we're going to talk about today is
trying to understand motor control or

how's nervous system control motion
after you've had an amputation.

So it's been a long road and this road for

me just like all the other presentation
going to see today started with M S P O.

When I was an M.S.P. Student my capstone
research project was what kicked off what

I've actually doing now in the Ph D.
and will hopefully continue to work on as

I get into a prosthetic residency and
then beyond within this within this

profession and one thing about this
pathway that I'm taking on as well as

a lot of other pathways that the we're
all taking right now in your research or

clinician or anything is that we're
all very interested in movement.

You know whether or not most was moving
with the prostheses or movement in general

and movement as any general movement
where you're fighting ninjas or

rebuilding engines or
running around your superman costume.

There's a lot of very similar traits
to movement that allow you to study

basically motor control with
with a lot of her movements and

can can look at
the fundamentals of that and

that's what we try to do so
that kind of gets healthy about mu.

I'm and since it's going to be ever
gold everyone else presentation

I thought of you little bit
about movement how that occurs.

So if you happen to be the scandalous guy
in anatomy textbook back in the fifty's

hundreds and you want to move through your
all of gardener award ever use trying

to move through several
things have to happen.

You're going to have a nervous
system is going to send out a series

of those commands.

They're going to activate some muscles
some of these muscles are going to be very

large more geared to generate the massive
mechanical energy you're going to propel

yourself through this the environment and
then the nervous system also has to figure

out how to coordinate additional
additional muscles so that the energy

created by these up here can then
get transferred to the ground or

the end point in this case
has them as a foot and

then I can generate a force that will
interact with a guy's environment and

will hopefully be enough force
toward this person to move and

this sort of scenario this sort of thing
has to happen pretty much with any motion

the type of motion that that we
concentrate on is cycling cycling

like walking as a rhythmic motion is
controlled by generally the same mechanism

of the spinal cord and the reason we
choose cycling to study motor control

is because it's a little more reduced when
you're walking you have to do two things

at once you have to balance yourself and
propel yourself at the same time and

with cycling I got to do so
in the saddle so

you have to balance yourself anymore and
so

now the nervous system only has been
certain with how do you propel yourself.

And so this potion that or

the build a separate balance
propulsion during this one task.

This also rhythmic just
like walking allows you to

really focus on a lot of other
sort of motor behaviors and

try to understand motor control in
a little bit cleaner environment and

addition although there are more contact
points than just the feet others

like the hands but because that's above
the saddle we're mostly concerned about

how this person propelling yourself which
is all goes down to how you're able to.

Contract all these muscles courting
that activity get force in the pedal.

So you can turn these cranks and so

that's the basic aspect of cycling that
we're just and starting motor control what

really interests me as far as amputation
and some things that are different.

Once you have an amputation
is that your leg is now

very different imagine that you
just had a portion of a removed.

You've had some muscles physically or
movies had other muscles modified like

the gas struck me me as a single joint
me flex or instead of knee flex or

ankle extensor but you still retain all
of these muscles up there on the fire.

So all these things from actual
see throughout this presentation.

Basically the residual You know you kind
of get an idea just fairness so different

red lines represent different muscles
just as a conceptual diagram and so

not only have to deal with the slam that
then compromise or portions been removed.

You also have to deal with this prosthetic
socket this mechanical device that you've

put on the end here and so now the person
must knowing the Goetia what's going on

this leg and
what what the person has left of the sled.

But now how they negotiate the prostheses
to turn these cranks will propel

themselves and

like I said This forms the basis
of how we study motor control and

that because this is
a motor tasks rhythm it and

involves the same processes involved in
the movement you can translate a lot of

this to try to understand how people
are moving through like running or

walking or swimming cycling it's all
all basically the same rhythmic task

now me saying that me using cycling
a lot of people immediately

think about how how best to adapt
the bicycle to some that want to cycle.

I'm not I'm not really going into how
to talk about getting people with

an education on a bike
even using a bicycle.

Although that is a passion of mine.

If you're interested in
that later in May for

the getting to try foundations
going to have their annual.

Get together here I teach
the amputee cycling portion of that.

So you have any patients that
are interested in cycling

we can go into that later.

They also take swimming and
running for amputees and

spinal cord injury but
we're going to continue just

mostly a motor control on the fundamentals
of motor control and how that's different.

After you've had an amputation.

And so I can mention when I started
this pathway with M.S.P. Program as.

As my capstone research project and
that project.

We looked at several things and

some of that's just now finally
getting out and getting published

one of the things I was concerned about
are our symmetries we know it's a mature

exist what if you had amputations one limb
produces forces differently than the other

turns out that also happens
the cycling is as no surprise.

So yeah we know that there are a symmetric
but one of the things proposed

as to why there is symmetric is that
one limb weighs less than the other so

the prosthesis weighs less than
the limb that was removed those and

also they have atrophy of one limb
hypertrophy of the other limb.

So the strength or inertial differences
between limbs may have an influence

on this and that may really explain the
symmetry in my master's project my it must

be zero Project found out
that it really doesn't yet

has an influence but it doesn't
explain what's actually going on.

So there's a lot of other things going
on about how this person can control

this motion.

This is not just related to spring for
Hershel differences.

Another thing we looked at
what in the past and what

continues will keep me on this pathway to
understanding this is polling technique so

if you think you know you don't
just have one amputated side

you just will have one sound amused both
limbs together to perform a task and so

one question arises woke a well is
this technique the same to someone.

I'm having a bicycle pedal it generally
the same way when you look at the whole

body combined and

it turns out that they do so
whether or not you have an amputation

you're still going to the same sort of
telling technique and so that's important.

Understand that.

OK you can't really necessary.

Look at these whole body kind of measures
need to look within side the limb

look look deeper look at what's
happening within joints.

What's happening with muscle activation
those were things you can explain this

stuff by just looking at
the total task performance.

Another thing that could of
really screw things up for

me was the fans who are electro
mechanical delay which basically says

does another resist on what you've had a
few Taishan realize that the properties of

this muscles different and does it take
into account the properties of muscle and

how the the muscle contraction the speed
at which contracts as it moves forward

after it's had a stampede Taishan So
it turns out that doesn't change which is

really awesome so whether or not you've
had amputation doesn't matter your nervous

system still realizes that the muscles
going to contract to a certain speed is

going to have these certain sort of
mechanical dynamics were properties to

it and it maintains that even
after the amputation which allows

us to look even deeper and
understand things even even even closer.

Well that and so

that leads me to think OK well what
are the things that are going on here.

And so one of the big questions is Is
it the altered mechanics is it because

the system is now different you know
is it does it go back to this leg is no

longer like this leg this leg now ins here
you have to do with the prostheses and

do these mechanics have been altered help
explain what's really going on especially

when it comes down to control
control this propulsive pass and so

that that underlines basically my
dissertation as I move forward and

I'll be in June fourteenth at nine A.M.
for those that are interested.

An hour to do that.

I grab eighteen volunteers or or
victims whatever whatever word you

prefer nine of them had tranced only
amputation they're all traumatic

amputees they're all very skilled at
using the prostheses they were not there.

They're familiar with cycling but
they weren't skilled at cycling so

they use cycling more.

Recreational there no Parlin billions or
anything like that.

So we took we were crew of those
nine transitively amputees.

And then we created nine intact
individuals with similar sort of

psych experience so that that skill
that motor skills social cycling's kind

of taken out of the picture.

And we have them all peddle at a hundred
fifty watts ninety R.P.M. which is a very

moderate pace very standard loading
cadence condition for cycling.

And while they cycle we took a bunch
of measurements we took a bunch of

measurements of when their muscles
were turning on we were turning off so

we had the surface seem to be of
over twelve muscles on both legs so

we're able to get an example of
every major muscle group for

the amputees on their
sound an amputated limb.

We took pedal forces so

we knew the forces between the foot in the
pedal with these instrumented force poles.

If you forces in all sorts of directions
and spin and all kinds of data.

We then took the motion of
the joint through a sixty six

camera infrared motion system that some of
these other M.S.P. estimates have used.

I use a peak performance
was the system I used.

It's kind of the outdated
predecessor by Constance

which is what's currently being used.

And then for that you can calculate what
moments are the torque of each joint so

you know the mechanical loading in each
joint so on this a little bit different

about how I've done this versus more
traditional ways by mechanics mistyping

with amputees is on the top of that minute
first want to talk about the prostheses

So generally we made we
fabricated prostheses for

each person we duplicated their
socket using tracer CAD so

they were is a difficult socket except
everyone use pence especially when

I tell you why in a second and
then everyone uses this magnificently

comfortable to walk in chunk of aluminum
foot this way the mechanical process

properties of prostheses were constant
across all subjects and it turns out that.

Hunks of aluminum are actually better for
cycling performance so there you go.

Steph equals good for cycling not
necessarily good for walking and

then also we did this pilot study where
we developed this system before I

had the camera system on how to
measure motion of the distal and

of the of the of the limb and
how that moves in the socket was cycling.

So we had this big crazy contraption turns
out what we learned is that it only has

a couple millimeters.

And since it only comes in a couple
millimeters we assume then that

the this becomes a kind of pseudo joint.

So we put a marker there so we can know
where the end of the residual limb is so

we can look at that as a as a hinge
point if you will we have the normal

ankle marker and then we remove
the ladder wall the prostheses so

we can put the marker where the knee joint
actually is so as the knee moves around

the socket we can track that and then
we can get by with removing the ladder

wall the socket in cycling because
the frontal plane forces are next to zero.

I mean they're very very small
especially compared to walking so

you really don't need that
ladder wall at least for

cycling once you get off the bike and
start running that's a little different

and what we learn from that is that
the limb is a lot of the socket.

So this is this is the how the limbs
moving in the socket the angle of

the limb relative to the prostheses OK So
all these graphs the X.

axis is will always be the crank cycle
start with the crank up being top and

center would be zero the crank ninety
degrees down one hundred eighty degrees so

this would be the power phase of the
person's push down on the on the crank and

then the recovery phase as the as the
crank comes back up and what this shows us

is the limbs pretty much in line with
the prostheses at the bottom of the pedal

stroke and then the knees basically
moving more post to really relative

the socket as it comes back out and then
as it comes back over the top of this.

The pedal stroke to start
stretching back out again and so

now that we know we can track that
movement we can then look at other things

like muscle activation to try to
explain why we see these differences.

So this is the muscle activation of the
rectus femoris So it's a hip joint flex or

need to an extent serve
to joint muscle this

yellow shaded region is the intact
group so this is normal.

This is the main plus or
minus one standard deviation then that

the mean plus or
minus one standard deviation you go and

it's this this sort of gold or yellow band
with this one hump and then the later home

is very normal especially for two joint
muscles expression during cycling what we

didn't expect to see and what we actually
saw here this black line is the mean and

then these thin black
lines are the plus or

minus one standard deviation this is that
if they're missing this this whole first

home that the muscles just basically not
turning out at all there anymore and

that's very unusual sense you know if it
wasn't amputated there's really nothing

wrong with it for some reason
the people using this prostheses for

cycling has decided that they just no
longer want to turn on the muscle and

the other unusual bit we
got we also took I mean

besides taking the muscle activation of
all the other muscles which didn't really

change much for another one and then
change a lot was the gas truck medius So

we're taking that information from
within the side of the socket and

we've got some very different
activation pattern there as well.

So once again this gold is normal the so
this is an intact person are the sound

limb of a amputee they look identical
typical biodiesel kind of activity

pattern that is this associated with
with normal to join muscle occupation.

When you look at they if you tease and
their peak where there's a.

One peak and then that peak falls between
these two it's completely different and

the muscle is also now
completely different.

I mean it's been surgically altered
to one joint muscle it no longer

controls the ankle joint.

And so that's very neat.

And so we start thinking about what
a well why and why is this different.

Why did these muscles change.

One reason could be well the case of
gastric Mimi is that one joint muscle now.

So the need part about that is it is one
joint and the nervous system figured that

out decided it's going to use it and that
the net fashion and one way to kind of

show that is that there's a lot of work
work on how do you classify muscles and

how to the motor system recognise things
one way is of the peak of that muscle

forces are the peak of that activity
happens just before the peak joint moment.

That's one way and
that's what's happening here.

So like I said this is that given
the curve of the gas mark MEUs that we've

seen for a while now this bottom is
the knee joint moment was the torque about

the knee joint and so

this if it's positive it's an extensor
moment it's negative as a flex or moment.

And so

if we're going to keep our concentration
here at the bottom of the pedal stroke.

You can see there's a peak or moment.

That's just happens just after
the peak activity of that muscle.

So if you look back at work by fanning and
she now you'd

say that a single drop muscle the systems
recognise that but also what's happening

is that this person must also control
prostheses before can control the pedal.

And so if you think about what's happening
at the bottom of the pedal stroke

your the limbs come down.

There's a lot of inertial forces
as this big heavy limbs used

to be going down now being drawn.

I guess post to really
sort of come back out.

You would like to direct force as
opposed to really to kind of keep

that crank moving around and
the only way to do that or

one of the ways to do that is to contract.

This gas truck name is to keep the knee
joint closer to the anterior wall

of the socket and you can kind of effect
the the this will end of the residual limb

toward the Post your wall the socket to
kind of you will look that prostheses and

kind of keep it going moving through and
so if that's the case you'd also

expect to see a large flex or
moment for the the joint at this pseudo

limb prostheses joint that we're talked
about earlier of the marker right there.

And that's what happens which is awesome.

So this is the moment between the the
moment the joint between the residual

limb of the prostheses and you see a nice
big large flex from moment there and

it came that indeed this muscle was not
only controlling the prostheses but

it's using that in order
to control this task

as we would come to the bottom of pedal
stroke when we start going back up.

You notice the the this angle starts
changing the knee starts moving

further back.

So you're now in this configuration.

Not many muscles are active here so

there's not a whole lot to prevent the
socket from moving around at this point

it's pretty much at the mercy of inertial
forces and and the properties of

the soft tissue of the limb turns out
the back of casts pretty soft and so

the prostheses moves on the limb and
so this is where this initial

change in the orientation the limb
relative the socket occurs.

What sets you up for
the top of the pedal stroke

which brings us back to our breakfast
femoris So the top of the pedal stroke.

You have the limb kind of
cocked within the prostheses

you have the Post your wall being driven
in the poster aspect of the knee and

if you ever work with anyone that
that tells a bicycle they'll tell you

this is their number one complaint is
pressure back their discomfort back there.

Well now if you look at the lead in
this configuration you think about.

OK.

If I wanted to transform force this
way and start generating a larger and

the extensor moment for the in preparation
for the power phase you'd want to

activate the righteous farmers in fact
that's what an intact person does that's

that's part of the picture but if you're
in this configuration you start activating

that rectus femoris Now all you going
to do is drive the distal of the tibia

into the hands here portion the socket
people don't usually like that one.

If an application and you go drive
the Post your wall the socket further

into the post you're aspect
of the name you know what.

Like that either.

So somehow the nervous
system is figure that out

figured out that snot really
good way of doing things and

has decided that it's just no longer going
to activate and that portion anymore.

And so kind of taken together we're
saying that the person has changed

its muscle activity and is using the
muscles to not only control the task but

control the limb within the sockets
controlling this interface about

how this person can use the socket
this prostheses to do this task or

pretty much any movement task and
so what that means for

our skinless guy again is that if you
gave a skinless here and you Taishan

you get more prostheses now you got to
realize that the endpoint of the nervous

system in the end point of this motor
system is now the residual limb.

It's no longer the foot
the foot is gone and

what's been replaced with this mechanical
device and now he must control

this prostheses in order to control
what's happening in his environment.

So if you take that in a different
context the prosthesis is a tool.

So the motor system views
the prostheses as a tool now.

And so in order to control what's
happening at the end point

the control of the tool you must affect
what's happening at the interface and so

in order to control the endpoint you must
control the interface differently than if

you would if you didn't have the tool.

And so if we see these motor
changes associate was trying to

control the center face and
using this prosthesis as a tool.

Well that that leads me to
kind of wonder something else.

This is a very broad question that that
you can think about today is as you move

through your clinical practice and
that is well then what is a gay deviation

because we've always defined gay
deviations deviations from normal or

deviation from someone intact while
skinless here is no longer intact.

This is his new normal.

So in fact he may not be
deviating from Norm he may just

be using this prosthesis as
a tool in a different way and so

it really what what we like calling the
evasions may just be motor adjustments and

so these adjustments occur because
of the properties of prostheses and

because of the way it's been design which
is really cool as we move down our road

further in this practice and
you know we may get lost along the way but

now we can start thinking about OK if this
process is a tool in the person views

this process of tool how can
we change the prostheses or

the design better prostheses
that take advantage of this and

then as we move in the future hopefully
we can design better prostheses and and

affect clinical care and
in a positive outlook.

That's pretty much the conclusion of us
want to point out we have a couple present

take our couple of we've been publishing
a lot of the background information both

within the journal privacy cloud
biomechanics prospects for

Fox International we have one paper
published another one review and

then we have a couple textbooks and
then of course if you're interested more

in how to get people on bicycles or
how to get people up and

running are your patients up and
running and set of the motor control that

then the getting try foundations
in your meeting is coming up.

And that's it.

Thank you very much.

Leigh if you take one
question two questions from

the audience first.

So you guys this is.

You know

your old ride.

Well if you're right.

So we saw those very different changes and
muscle activity

there related to how the person has to
control the limbs like interface and or

control the pedal and that's the basis.

What.

So if I was looking

at some kind of basis for

your what was was there one.

So I think the presentation was about
the differences between the two right.

So the rule was that

it's sort of the difference occur
in all the amputees that we study.

Yes.

Yeah it's clear difference and everyone.

Thank you very much.