the stuff of life meets machine
this is our motivation arm amputation causes a huge disability i mean the functional impairment is clear our hands are amazing instruments
and when you lose one far less both it 's a lot harder to do the things we physically need to do there 's also a huge emotionalimpact and actually i spend as much of my time in clinic dealing with the emotional adjustment
arm amputation is usually caused by trauma with things like industrial accidents motor vehicle collisions or very poignantly war there are also some children who are born without arms called congenital limb deficiency
for an arm in one thousand nine hundred and twelve 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 a 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 myoelectric prostheses 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 antennae or electrodes and use that to operate the motorized prosthesis
they work pretty well for people who have 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
well our patients have to use very code y systems of using just their arm muscles to operate robotic limbs
we have robotic limbs there are several available on the market and here you see a few they contain just a hand that will 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 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 u s military using these prototypes that had up to ten different degrees of freedom including movable hands
but at the end of the day how do we tell these robotic arms what to do how do we control them
and your sensation 's the 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 nervoussystem still works those nerves can put out command signals and if i tap the nerve ending on a world war ii vet he 'll still feel his missing hand
so you might say let 's go to the brain and put something in the brain to record signals or in the end of the peripheral nerve and record them there and these are very exciting research areas but it 's really really hard
you have to put in hundreds of microscopic wires to record from little tiny individual neurons ordinary fibers that put out tiny signals that are microvolts
and 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 thousand fold 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 close hand and a little section of your chest contracts you think bend elbow a different section contracts and we can use electrodes or antennae to pick that up and tell the arm to move
jesse came to us at the ric to be fit with these 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 revisionsurgery on his chest and that gave us the opportunity to do targeted reinnervation
so my colleague dr greg dumanian did the surgery first we cut away the nerve to his own muscle then we took the arm nerves and just kind of had them shift down onto his chest
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 antennae or electrodes and i challenge anybody in the room to make their chest go like this
his brain is thinking about his arm he has 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 he 's had that arm for about twenty months so he 's pretty good with it
on the right side two months after we fit him with his targeted reinnervation 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 in science 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 hand sensation grew into his chest again probably because we had also taken away a lot of
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 hand imagine sensors in the hand coming up and pressing on this new hand skin so it was very exciting
we 've also gone on with what was initially our primary population of people with above the elbow amputations and here we deinnervate or cut the nerve away just from little segments of muscle
and leave others alone that give us our up down signals and two others that will give us a hand
open and close signal this was one of our first patients chris you see him with his original device on the left there after eight months of use and on the right it is two months he 's about four or five times as fast with this simple little performance metric
amanda would you please tell us how you lost your arm
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
to get it to change modes when i did
cocontract again to get the elbow to work again
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 cocontracting and all that
the success rate of the nerve transfers is very high it 's like ninety six percent because we 're putting a big fat nerve onto a little piece of muscle and it provides
and we wanted to get more you can move each finger you can move your thumb
and recorded this data and then we used some algorithms that are a lot like speech recognition algorithms called
commercial components from here down and a few that i 've borrowed from around the world it 's about seven pounds which is probably about what my arm would weigh if i lost it right here obviously that 's heavy for amanda and in fact
so the exciting part isn 't so much the mechatronics but the control so we 've developed a small microcomputer that is blinking somewhere behind her back and is operating this all by the way she trains it to use
her individual muscle signals so amanda when you first started using this arm how long did it take to use it
here 's amanda using an arm made by deka researchcorporation and i believe dean kamen presented it at ted 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 grasps what we do is have the patient go all the way open and think
feel sensation through
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 've got a real estate problem
the future is bright we 're excited about 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 muscles and telemeter out the emg 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
so rather than a super strong or super fast arm we 're making an arm that is
we really appreciate you 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 lagged she 's using the arm
but i have a really bright research team and thankfully dr annie simon was with us
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