A prosthetic arm that feels Todd Kuiken
so today I would like to talk with you
about bionics which is the popular term
for the science of replacing part of a
living organism with a mechatronic
device or a robot it is essentially the
the stuff of life meets machine and
specifically I’d like to talk with you
about how bionics is evolving for people
with our man pute Asians this is our
motivation our man tation causes a huge
disability I mean the functional
impairment is clear our hands or amazing
instruments and we lose one far less
both it’s a lot harder to do the things
we physically need to do there’s also a
huge emotional impact and actually I
spent as much of my time in clinic
dealing with the emotional adjustment of
patients as with the physical disability
and finally there’s a profound social
impact we talk with our hands we greet
with our hands and we interact with the
physical world with our hands and when
they’re missing it’s a barrier arm
amputation is usually caused by trauma
with things like industrial accidents
motor vehicle collisions or very
poignant Lee War there are also some
children who are born without arms
called contingent limb deficiency
unfortunately we don’t do great with
upper limb prosthetics there are two
general types they’re called body
powered prosthesis which were invented
just after the Civil War refined in
World War one in World War two here you
see a patent for an arm in 1912
it’s not a lot different than the one
you see on my patient they work by
harnessing shoulder power so when you
squish your shoulders they pull on a
bicycle cable and that bicycle cable can
open or close a hand or hook or Bend an
elbow and we still use them commonly
because they’re very robust and
relatively simple devices the state of
the art is what we call mile electric
pressed
these are motorized devices that are
controlled by little electrical signals
from your muscle every time you contract
a muscle it emits a little electricity
that you can record with antenna or
electrodes and use that to operate the
motorized prosthesis they work pretty
well for people who’ve just lost their
hand because your hand muscles are still
there you squeeze your hand these
muscles contract you open it these
muscles contract so it’s intuitive and
it works pretty well
but how about with higher levels of an
amputation now you’ve lost your arm
above the elbow you’re missing not only
these muscles but your hand in your
elbow too what do you do well our
patients have to use very kody systems
of using just their arm muscles to
operate robotic limbs
we have robotic limbs there are several
available on the market here you see a
few they contain just a hand that’ll
open and close a wrist rotator and an
elbow there’s no other functions if they
did how would we tell them what to do
we’ve built our own arm at the rehab
Institute of Chicago where we’ve added
some wrist flexion and shoulder joints
to get up to six motors or six degrees
of freedom and we’ve had the opportunity
to work with some very advanced arms
that were funded by the US military
using these prototypes that had up to 10
different degrees of freedom including
moveable hands but at the end of the day
how do we tell these robotic arms what
to do how do we control them well we
need a neural interface a way to connect
to our nervous system or our thought
processes so that it’s Intuit if it’s
natural like for you and I well the body
works by starting Akimoto command in
your brain going down your spinal cord
out the nerves into your periphery I’m
cutting and your sensations exact
opposite you touch yourself there’s a
stimulus that comes up those very same
nerves back up to your brain when you
lose your arm that nervous system still
works those nerves can put out command
signals and if I tap the nerve ending on
a World War 2 vet he’ll still feel is
missing hand so you might say let’s
let’s go to the brain and put put
something in the brain
record signals or into the end of the
peripheral nerve record him there and
these are very exciting research areas
that’s really really hard you have to
put in hundreds of microscopic wires to
record from little tiny individual
neurons or nerve fibers that put out
tiny signals that are there micro volts
and it was just it’s just too hard to
use now and for my patients today so we
developed a different approach we’re
using a biological amplifier to amplify
these nerve signals muscles muscles will
amplify the nerve signals about a
thousandfold so that we can record them
from on top of the skin like you saw
earlier so our approach is something we
call targeted reinnervation imagine with
somebody who’s lost their whole arm we
still have four major nerves that go
down your arm and we take the nerve away
from your chest muscle and let these
nerves grow into it now you think closed
hand and a little section of your chest
contracts you think bend elbow a
different section contracts and we can
use electrodes or antennas to pick that
up and tell the arm to move that’s the
idea so this is the first man that we
tried it on his name is Jesse Sullivan
he’s just a saint of a man 54 year old
lineman who touched the wrong wire and
had both of his arms burnt so badly they
had to be amputated at the shoulder
Jesse came to us at the RIC to be fit
with the state-of-the-art devices and
here you see them I’m still using that
old technology with a bicycle cable on
his right side and he picks which joint
he wants to move with those chin
switches on the left side he’s got a
modern motorized prosthesis with those
three joints and he operates little pads
in his shoulder that he touches to make
the arm go and Jesse’s a good crane
operator and he did okay by our
standards he also required a revision
surgery on his chest and that regain us
the opportunity to do targeted
reinnervation so my colleague dr. Greg
damayan
did the surgery first we cut away the
nerve to his own muscle then we took the
arm nerves and just kind of had him
shift down onto
chest and closed him up and after about
three months the nerves grew in a little
bit and we could get a twitch and after
six months the nerves grew in well and
you could see strong contractions and
this is what it looks like this is what
happens when Jesse thinks open and close
his hand or bend or straighten your
elbow you can see the movements on his
chest and those little hash marks are
where we put our antennas or electrodes
and I challenge anybody in the room to
make their chest go like this his brain
is thinking about his arm he’s not
learned how to do this with the chest
there is not a learning process that’s
why it’s intuitive so here’s Jesse in
our first little test with him on the
left-hand side you see his original
prosthesis and he’s using those switches
to move little blocks from one box to
the other had that arm for about 20
months so he’s pretty good with it on
the right side two months after we fit
him with his target Adrina vation
prosthesis which by the way is the same
physical arm just programmed a little
different you can see that he’s much
faster and much smoother as he moves
these little blocks and we’re only able
to use three of the signals at this time
then we had one of those little
surprises and science
okay so we’re all motivated to get motor
commands to drive robotic arms and after
a few months you touch Jesse on his
chest and he felt his missing hand his
hands sensation grew into his chest skin
probably because we had also taken away
a lot of fat so the scanner is right
down on the muscle and D nerve ated if
you would his skin so you touch Jesse
here he feels his thumb you touch it
here he feels his pinky
he feels light touch down to one gram of
force
he feels hot cold sharp dull all in his
missing hand or both his hand and his
chest but he can attend to either so
this is really exciting for us because
now we have a portal a portal or a way
to potentially give back sensation so
that he might feel what he touches with
his prosthetic an imagined sensors in
the hand coming up and pressing on this
new hand skin so it’s very exciting
we’ve also gone on with what was
initially our
primary population of people with above
the elbow amputations and here we D
nerve 8 or cut the nerve away just from
little segments of muscle and leave
others alone that give us our up-down
signals and to others that will give us
a hand open closed signal this was one
of our first patients Chris you see him
with his original device on left there
after 8 months of use and on the right
in just 2 months he’s about I don’t know
four or five times as fast with this
simple little performance metric I don’t
write so one of the best parts of my job
is working with really great patients
who are also our research collaborators
and we’re fortunate today to have Amanda
Kitts come and join us please welcome
Amanda Kitts
so Amanda would you please tell us how
you lost your arm
sure in 2006 I had a car accident and I
was driving home from work and a truck
was coming the opposite direction came
over into my lane ran over the top of my
car and his axle tore my arm off okay so
after your amputation you healed up and
you’ve got one of these conventional
arms can you tell me tell us how it
worked well it was a little difficult
because all I had to work with was a
bicep and a tricep so for the simple
little things like picking something up
I would have to bend my elbow and then I
won’t have to co contract'
to get it to change modes when I did
that I had to use my bicep to get the
hand to close use my tricep to get it to
open
kokin tracked again to get the elbow to
work again so it’s a little slow a
little slow and it was very it was it
was just hard to work you had to
concentrate a whole lot okay so I think
was about nine months later that you had
the target reinnervation surgery took
another six months to have all the
reinnervation then we fit her with a
prosthesis and how did that work for you
it worked
good I was able to use my elbow and my
hand simultaneously I could work them
just by my thoughts so I didn’t have to
do any of the coking tracting and all
that little faster it was a little
faster much more easy much more natural
okay this was my goal okay for 20 years
my goal was to let somebody able to use
their elbow and hand in an intuitive way
and at the same time and we now have
over 50 patients around the world who
have had this surgery including over a
dozen of our wounded warriors in the US
Armed Services the success rate of the
nerve transfers is very high it’s like
96 percent because we’re putting a big
fat nerve onto a little piece
muscle and it provides intuitive control
our functional testing those little
tests all show that they’re a lot
quicker and a lot easier and the most
important thing is our patients have
appreciated it so that was all very
exciting but we want to do better okay
there’s a lot of information in those
nerve signals and we wanted to get more
you can move each finger you can move
your thumb your wrist can we get more
out of it so we did some experiments
where we saturated our poor patients
with zillions of electrodes and then
have them tried to do two dozen
different tasks okay from wiggling a
finger to moving a whole arm to reaching
for something and recorded this data and
then we use some algorithms that are a
lot like speech recognition outcomes
algorithms called pattern recognition
see and here you can see on Jesse’s
chest when you just tried to do three
different things you can see three
different patterns okay but I can’t I
can’t put an electrode to say go there
so we collaborated with our colleagues
in University New Brunswick came up with
this algorithm control which a mannequin
now demonstrate so I have the elbow it
goes up and down I have the wrist
rotation that goes and they can go all
the way around and I have the wrist
flexion and extension and also have the
hand close and open Thank You minna no
this is this is a research arm but it’s
made out of commercial components from
here down and a few that I’ve borrowed
from around the world it’s about seven
pounds which is probably what about what
my arm would weigh if I lost it right
here
obviously that’s heavy for Amanda and in
fact it feels even heavier because it’s
not glued on the same she’s carrying all
that weight through harnesses so the
exciting part isn’t so much the the
mechatronics but the control and so
we’ve developed a small micro computer
that is blinking somewhere behind her
back and is operating this all by the
way she trains it to
use her individual muscle signal so
Amanda when you first started using this
arm how long did it take to use it I
took just about probably three to four
hours to get it to train I had to hook
it up to a computer so I couldn’t just
train it anywhere so like if it stopped
working I just had to take it off so now
it’s able to train with just this little
piece on the back I can wear it around
if it stops working for some reason you
can retrain it takes about a minute so
we’re really excited because now we’re
getting to a clinically practical device
and that’s that’s where our goal is to
have something clinically pragmatic to
where we’ve also had Amanda able to use
some of our more advanced arms that I
showed you earlier here’s Amanda using
an arm made by Decca Research
Corporation and I believe Dean came and
presented it at Tech a few years ago so
Amanda you can see has really good
control it’s all the pattern recognition
and it now has a hand that can do
different grass what we do is have the
patient go all the way open and think
what hand grass pattern do I want it
goes into that mode and then you can do
up to five or six different hand grasps
with this hand Amanda how many were you
able to do with the DECA arm I was able
to get four I had the key grip
I had a Chuck grip I had a power grass
and I had a find pinch but my favorite
one was just when the hand was open
because I work with kids and so all the
time you’re clapping and singing so I
was able to do that again which was
really good that hands not so good for
clapping can’t clap what those are so
that’s exciting on where we may go with
the better mechatronics if we make them
good enough to put out on the market and
use in a field trial once you watch
closely
that’s Claudia and that was the first
time she got to feel sensation through a
prosthetic she had a little sensor at
the end of her prosthesis that then she
rubbed over different surfaces and she
could feel different textures of
sandpaper different grits ribbon cable
as it pushed on her renovated hand skin
she said that when she just ran it
across the table it felt like her finger
was rocking so that’s an exciting
laboratory experiment on how to give
back potentially some skin sensation but
here’s another video that shows some of
our challenges this is Jesse and he’s
squeezing a foam toy and the harder he
squeezes you see a little black thing in
the middle that’s pushing on his skin
proportional to how hard he squeezes but
look at all the electrodes around it I
got a real estate problem I’m supposed
to put a bunch of these things on there
but our little motors making all kinds
of noise right next to my electrodes so
we’re really challenged on what we’re
doing there the future is bright we’re
excited where we are and a lot of things
we want to do so for example one is to
get rid of my real-estate problem and
get better signals we want to develop
these little tiny capsules about the
size of a piece of risotto that we can
put into the mussels and tool eMeter out
the mg signals so that it’s not worrying
about electrode contact and we can have
the real estate open to try more
sensation feedback we want to build a
better arm
okay this arm the are they’re always
made for the 50th percentile male which
means they’re too big for 5/8 of the
world so rather than a super strong or
super fast arm we’re making an arm that
is we’re starting with the 20th 25th
percentile female okay
that will have a hand that wraps around
opens all the way to degrees of freedom
and a wrist and an elbow so it’ll be the
smallest and lightest and the smartest
arm ever made once if we can do it that
small it’s a lot easier making them
bigger so those are just some of our
goals and we really appreciate all being
here today I’d like to tell you a little
bit about the dark side with yesterday’s
theme
so Amanda came jet lag she’s using the
arm and everything goes wrong idea there
was a computer spook a broken wire a
converter that sparked we took out a
whole circuit in the hotel and just
about put on the fire alarm and none of
those problems could I have dealt with
but I have a really bright research team
and thankfully dr. Annie Simon was with
us and worked really hard yesterday to
fix it that’s science unfortunately the
work today
so thank you very much