Albert Chi, MD, Trauma Surgeon, Medical Director of the Targeted Muscle Reinnervation Program at Oregon Health & Science University talks about targeted muscle reinnervation surgery that allows amputees to control advanced prosthetics with intuitive thought.
Interview conducted by Ivanhoe Broadcast News in November 2017.
What is targeted muscle reinnervation?
Dr. Chi: Targeted muscle reinnervation is a pretty unique surgery that allows amputees to control advanced prosthetics with intuitive thought. What we do is we take nerve endings that used to travel to the missing limb, reroute them to residual muscles that are still there. Now we can actually take that information that used to be traveling to nothing and have a way to actually record from it, amplify it and translate that to useful movement.
That sounds like science fiction.
Dr. Chi: It kind of does, but it’s amazing. It’s really based off our knowledge of neuroanatomy and the body’s amazing ability to really heal and to kind of preserve natural function that was once lost.
How long, is it a series of surgeries, can you do it one time, how does that work?
Dr. Chi: It’s actually one surgery and the really hard portion of the prosthetic fitting is the rehab and everything that is required afterwards. Most of my patients, honestly all of my patients are so dedicated that they go home they start mental imagery exercises after two weeks, we see them at two, four and six months and by that sixth month period they’re ready to go with their advanced prosthetic.
You’ve got to re-train, is it more difficult for some people? What is the imagery that you’re using to make it work?
Dr. Chi: Just imagine you’re missing your limb and you ask someone to open their hand for them to visualize that there is a phantom limb that they conceptualize within their mind. However, in order to truly make it robust and repeatable for those signals that we’ve re-routed, we actually use a virtual reality system where an arm is represented and two-dimensional space but it’s a three-dimensional limb. They can actually make little changes within their mind and mental adjustments to find that perfect what I like to call symphony of information of muscle activity in order to calibrate for their hand open. We’ve got it actually to the point where it’s so robust we can have individual finger movement.
It’s so hard to wrap my brain around that, that you can with your own brain move your hands or wrists and elbows. When people come to you does it take a little bit of convincing, do they believe it?
Dr. Chi: The wonderful thing is literally I can connect them to the computer, actually in the comfort of my office here and show them demonstrations of using advanced algorithm movements that they still have intact. And allow them to experience that pattern recognition and advanced kind of control that we’re offering.
How long does it take to retrain them to be functional?
Dr. Chi: Once the surgery is successful and those reinnervations and connections have taken, it’s amazing how quickly it is. You know for basic movements honestly within the first visit … I tell the patients first we put on the training wheels, we take off the training wheels eventually you’ll be riding on your own. But within a few sessions and then within a few months we’re already adding multiple grips with pretty advanced control.
Lots of veterans coming backing missing limbs now and they lost them traumatically, maybe there’s damage to the nerve endings, who does it work for best and who won’t it work for?
Dr. Chi: Anyone with an upper extremity loss or amputee is eligible if you’re above elbow or shoulder disarticulation. The only contraindication would be if you had a brachial plexus injury meaning that the nerves are damaged more proximately and then those signals wouldn’t transfer down.
The surgery itself what are you doing in there?
Dr. Chi: Think of me as a surgical electrician and we find the nerve endings that are traveling to the different muscles and we literally find the connections, disconnect certain connections of redundant muscles that are there. We find the cut nerve endings that used to project to that missing limb and we literally rewire to them. It’s really like a surgical rewiring of the body.
Let’s talk a little bit about Johnny, what’s your history with working with Johnny?
Dr. Chi: Well Johnny, he’s more of a friend than he is a patient. We go back to 2011, but Johnny was my very first targeted muscle reinnervation patient. When we first met he knew that this was a relatively new procedure, that I had additional training but had not actually performed the procedure for a real patient; and he took a huge leap with me and we’ve been inseparable every since. His command and control with pattern recognition and targeted muscle reinnervation he has really been a champion for upper extremity amputees throughout the country and the world.
So he’d be on the highly successful end of who you are working with?
Dr. Chi: Absolutely, his control is phenomenal but not only that, Johnny’s courage and willingness to enter clinical trials and really push the envelope of cutting-edge technology and this really crossroads of man versus machine, it’s really inspiring. Johnny is the first individual in the United States to have an osteointegration implant which is a titanium implant that’s externalized that you can actually attach your prosthetic device to. He is the only person in the US to have both osteointegration and targeted muscle reinnervation. So Johnny really is a pioneer and a trailblazer in so many ways.
So there are two different things going on there?
Dr. Chi: Absolutely. Johnny has two very different cutting edge surgeries that he had.
Where do you go from here then? Your imagination could go wild with what you’re doing.
Dr. Chi: I had the privilege of working with modular prosthetic limb which is the world’s most advanced prosthetic limb system. You know most of these demonstrations are of how dexterous this limb is. But for people who don’t know, it’s also motor and sensory capable. So really the next huge hurdle I think within the academic and research community is to provide that sensory feedback.
You can feel things?
Dr. Chi: Absolutely.
That’s crazy, that’s amazing. And I read that you also work with kids with prosthetics. Tell me a little bit about that.
Dr. Chi: In addition to being involved with really advanced prosthetics, I’m also working with a philanthropic association where we build 3-D printed prosthetic devices for children with congenital limb loss. And it’s a wonderful organization, it’s unfair to really compare the two devices together but we build these wonderful prosthetic tools that in many ways are life-changing. The children can use them every day in their activities of daily living but it also helps their psycho social maturity. And also potentially gateway devices to more advanced prosthetic devices later on.
It makes them a cool kid. What else haven’t I asked you that targeted muscle reinnervation that you think is critical to be in the story?
Dr. Chi: Well it’s just that there are all these advanced surgical techniques out there and it really takes the courage of someone like Johnny in order to advance the field. And currently there really is a healthcare crisis as far as being; we can do these wonderful things but can then the patients be fitted with these advance prosthetics later on. And hopefully with continued good work that everyone is doing in this field and the courage of patients like Johnny that we can eventually overcome that hurdle.
Do you think hundreds of patients have this in the US, thousands?
Dr. Chi: The targeted muscle reinnervation, I would say we are in the thousands. I mean it’s becoming more mainstream and with wonderful exposure and interest like we are here today it just makes it that much more acceptable.
If somebody was interested in it they just google target muscle reinnervation and they’ll find somebody hopefully in their area that would do that?
Dr. Chi: So the answer is yes, but I think is a little more complicated than just having the surgery. I think true success with targeted muscle reinnervation is really the rehab program and institutional support you have. To perform the surgery is easy, the hard part really is the commitment of the rehab team and the patients afterwards.
So then you could maybe meet someone you know that does not have the ability to commit to this?
Dr. Chi: Absolutely. It’s a very heavy and personal vetting process. I always do a phone conversation, a meet to greet. I always almost have a support group of other patients tell them what’s really installed for them and the dedication that’s required. And the key really is I have a dedicated team for the virtual rehab and therapy and really me as a physician to be available to them because it can be very frustrating. You know we were talking about the mental imagery and how to think of moving a missing limb, if you ask someone to point a finger the direction or even the orientation of the finger it makes a difference. And a lot of times you have to take a deep breath, sit down and tell the patient that everything is going to be okay and really sit there with them almost as a virtual rehab coach to get them through it.
Awesome, thank you.
Dr. Chi: You want to talk more about the osteo? I realize I jumped right into it.
Yeah, just a little bit because I’ll touch on it now.
Dr. Chi: It’s a whole other clinical trial that he’s a part of and the combination between the two really is what makes Johnny unique. He’s the only one in the US.
It’s part of his bones?
Dr. Chi: Yeah. And that’s why I didn’t want to put anything on him. So I think when you do the filming talk to him. Tell me about this osteo and you can zoom in and you’re going to see the stump and rod literally.
What’s the benefit of it.
Dr. Chi: There’s no socket involved anymore. There’s actually some tactile feedback that you can get that transmitted through the bone and it is a natural extension of man and machine. I mean it is implanted within him, he takes his arm on and off. There’s no longer a shoulder harness that’s involved and he has complete free range of motion of his shoulders. If you ask Johnny; I’ll be honest when he first told me he wanted to be the first person to have osteointegration I was nervous for him. We don’t know long term infection risks or the durability of this design but if you talk to Johnny he does not have any buyer regret at all. He is more than happy that he was and now having a little more time under our belt I am so happy for him as well.
When did he get that?
Dr. Chi: 2014, it’s been two years now.
END OF INTERVIEW
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