Thanks, Jason. It's wonderful to be here. I have nothing to disclose. I'm here to talk about prosthetic rehabilitation of the amputated limb. Another way to think about it, past, present, and future for TMR. Prosthetics go back hundreds and hundreds of years, even thousands for this mummy toe found in a tomb in Egypt. But of course, we are making advances, and it has reached the popular literature. But this is the past. I don't need to hear anything, but this gentleman who has a high amputation is using his pectoralis major to drive prosthetically his elbow or his hand. But the pectoralis major was never designed to be giving those kinds of signals. The other problem is that he has to either move his elbow or his terminal device, but he can't move them both at the same time with the same signaling. This paper, as part of Todd Kiken's PhD work, talked about hyper-reinnervation of skeletal muscle. He's a physiatrist. He's an engineer, not a surgeon, a good friend. And his idea of trying to get information out of the amputated nerve kind of stayed where it was in 1995 until we had dinner together around 2000. Our wives were out of town, and he started telling me about his PhD thesis. And I was like, oh, that's just muscle and nerve surgery. We can do that tomorrow. And then this guy just walked into our office. He had painful neuromas and this painful skin grafted skin on his chest. And I said, why couldn't he be our first patient trying to get information out of the amputated nerve? And the goal was to take this one pectoralis muscle with a clumsy, dumb signal and to create four smart signals. Well, how would we do that? First, we went to the cadaver lab. I like to say that I bankrolled target innervation because I paid for this cadaver. We did some dissections and found out how far would these amputated nerves reach. Would they reach the area of motor nerves of the pectoralis to do a nerve coaptation or a nerve transfer? This is target innervation in a nutshell. Taking the amputated nerve, finding the small motor nerve going to a muscle segment, and doing a nerve transfer. That's Jesse Sullivan's image with four different nerve coaptations to divided pieces of his pectoralis major. And here he is two months after target innervation, after we had neuratization. He had used that prosthetic for two years. It's the same prosthesis. But now he can just think, I'm going to be moving my elbow or moving my terminal device. And he can move them smoothly, intuitively, and in the same time frame. So use of the prosthetic speeds up. Now, Doc, I don't have to think about what I'm doing. I just do it. Training is actually minimized when the muscle movement becomes intuitive. There are things that we've listed he can do better with an experimental prosthesis and new things that he could do. The TMR procedure takes two to four hours. It's one day in the hospital, no transfusions. And you can go back to wearing your original prosthetic as soon as you have healed wounds, usually three to four weeks. But when the movement becomes intuitive, you need less rehab. Todd and I started teaching friends. This is Oscar Osman in Vienna, who became an early proponent of TMR. And hundreds of TMR patients have been done worldwide now at many of these centers. Our success rate is in the order of 95%. Why? Because we have a large motor input. We have a lot of axons. And all we're doing is trying to get muscle signaling, an EMG signal. So one of those motor nerves grows into the muscle segment. And it becomes under cortical control after neurotization. And all you need is a signal. That signal is picked up by the prosthetic to move the terminal device. Some people have great challenges with soft tissues. But after free flaps and muscle flaps, smoothing out his soft tissues, this gentleman can now, he is the only bilateral TMR at this point that I know of. But he can move both prosthetics at the same time without really thinking. He's thinking about it. But he's not really concentrating on, how am I going to move my elbow joint? So for transhumeral TMR, I'd like to give a shout out to my residents who wrote this paper in last month's Journal of Hand Surgery. But it has some nice diagrams and cadaver work on how exactly what we're doing for both transhumeral and shoulder disarticulation TMR, taking, in this case, the small motor nerve to the medial head of the biceps, taking the median nerve and doing a nerve transfer. That movement of the median nerve to the motor nerve of the medial head of the biceps, that's all you do for transhumeral TMR for getting elbow flexion. This is a TMR-style nerve transfer higher up. Large, big nerve, small motor nerve coming out. But by standard nerve teaching, this sort of size mismatch should cause a painful neuroma. So what about neuroma formation? Why aren't these TMR nerve coaptations causing problems? Well, Germanic thinking, old way we were taught about peripheral nerve surgery, if things aren't lined up, it's going to be a problem. And I was very concerned about that when we started TMR. So we went and we created a rabbit amputee model, created neuromas, and took a muscle flap with three different nerve outputs and did three different nerve coaptations, trying to understand how the TMR nerve coaptation, with its size mismatches, was affecting the nerves. We got neurotization of the three nerve coaptations. And this is one of the more important slides I'm going to show. Before TMR, you have big axons with lots of myelin. When you have an established neuroma, small axons, lots of sprouting. But after TMR, the image on the right, the axons get bigger and you have myelin again, giving the nerve somewhere to go and something to do calms it down and, we think, takes away pain. TMR had less pain after surgery than before, despite these nerve mismatches. This was written up by several people on this panel, including Dr. Cho and Dr. Ko, CORE 2014, looking at our pain outcomes in 28 patients done in the military and at Northwestern. So what's the present? That was the past. Well, we're now doing TMR for both arms and legs. We have a randomized clinical trial of using TMR versus standard muscle burying for painful neuromas in amputees done at several centers. If you're interested and you have a similar patient, send them down. We'd be happy to enlist them in this study to find out, does TMR control pain better or equivalent to standard nerve burying? And what's the future? Well, so far, TMR is just used as an on-off signal. When the muscle is quivering, you pick up the EMG signal and that moves the device. But with pattern recognition, there is a complex lawn of myoelectric signals that's generated with movement. And so Jesse Sullivan, that first patient, when you put lots of sensors on, you can train the prosthetic of what to do. And this is the kind of outcome, even at the shoulder disarticulation level, you can get with pattern recognition and a really fancy arm. This isn't for take-home use. But there are now transhumeral devices that use pattern recognition to get exquisite individual finger motion. This patient is not mine. I'm not sure where I got this video. But this is a transhumeral amputee with a pattern recognition arm. And you can see that he has really fine control of his terminal device. Pattern recognition arms are now commercially available. So this is the future, essentially, right now. What about for legs? Well, pattern control, pattern recognition systems for lower extremity prosthetics. This was just made the New England Journal. Again, from my group, Todd Kaiken is on this paper. Osseointegration is really the next frontier. And this gentleman came in from Australia. These osseointegration systems are not available yet in the United States. But they are elsewhere worldwide. IMEs, IMEs are implantable sensors that we can put in the muscle to beam out the signal as opposed to sticky electrodes. And this is going to be a huge advance. Transfer sensation, using the sensation of the median nerve that's on the chest after targeted muscle innervation to then give a signal back to the brain of how hard the device is being used. And these are called tactors, where the pressure thresholds in the prosthetic device are being pushed on the skin, which has been re-innervated by the median nerve. And that gives the user the signal of how hard the device is used. And finally, improved neural interfaces. This is Paul Soderna, who is doing a great work on, I like to call it micro-TMR, using small muscle segments around amputated nerves to give off. And you can record the nerve signal in a much improved way, as opposed to putting a wire directly into the nerve itself. Current challenges, battery life, durability, signal acquisition, prosthetic wear time. And in terms of TMR versus hand transplantation, TMR cuts the nerves back and has a much shorter re-innervation distance to its target. It's the big philosophic difference between asking the nerve to grow distally or cutting the nerve back to where it's healthier. This is an amputated nerve, and we did serial segments. On the left, you can see a disorganized, mostly sensory nerve at the neuroma. But seven or eight centimeters back, you see axons with the pimento sign, red staining showing a motor cell. We, in target innervation, cut nerves back to where they're healthier. So I'm going to give a shout out. We're having a TMR symposium, May 12 and 13, next year in Chicago. Thank you for letting me present.

prosthetic rehabilitation

targeted muscle reinnervation

upper limb amputations

lower limb amputations

TMR symposium