Hand Transplantations and Bionic Prostheses
Recently I attended an international medical student congress, Medical Student Journal Club – Pro et Contra, which took place on 23. and 24. May 2014 in Ljubljana, Slovenia.
It was a great congress, with a lot of interesting debates preesented by great speakers.
Myself, I have also registred as an active speaker, together with a colleague of mine, Barbara Šijaković. We debated on topic “Reconstructive surgery should focus on development of cadaver body parts transplantation rather than bionic prosthesis implantation“.
Below is a transcript of our debate.
And just for elaboration, the whole keynote was actually made with only videos tu support theses.
Reconstructive surgery should focus on development of cadaver body parts transplantation rather than bionic prosthesis implantation
Luka: Hello, it’s me up here again. So, I thought I could start with an old Marx brothers joke. No wonder it looks like the same room, because it is the same room. Ok, it doesnt go…
Well, since it’s Saturday afternoon and this is the last debate of this congress, we’ll try to be as interesting and short as possible. My name is Luka, on my left a college of mine, Barbara, and, already introduced, our mentor, Nina Suvorov, MD.
Before we actually start with the debate, let us ask you a question. Imagine you’ve lost your hand sometime in the past and now you are presented with two options. Either hand transplantation or bionic prosthesis. Which would you, right now, choose. Would you go for hand transplantation, or would you rather go with a bionic prosthesis. How many of you would choose hand transplantation? And how many bionic prosthesis? Interesting; 60% for bionics and 40% for transplantation. We’ll keep that number in mind.
Barbara: Now, before we begin, let’s clear the terms. Luka, could you tell us what a reconstructive transplant is?
Luka: Thank you, Barbara. A reconstructive transplant, or also called a composite tissue allograft, is an operation that involves transplantation of bone, tissue, muscle and blood vessels. According to WHO “transplantation is the transfer or rather engraftment of human cells, tissues or organs from a donor to a recipient with the aim of restoring function(s) in the body. And in cases when transplantation is performed between different species, e.g. animal to human, it is named xenotransplantation.”
Now, Barbara, would you care to briefly explain what a bionic prosthesis is and how it works?
Barbara: Bionic creativity engineering is basically implementation of biological systems in the developing modern technology. Bionic hand isn’t just the hook. It mimics the real human hand. In some cases bionic hand even superposes human hand, as we shall see later.
There are different bionic prostheses, today I’ll talk about i-Limb Ultra, the one most advanced for now.
Here is how it looks: we can see power button here, the digits are motorized. It’s made out of plastic, titanium and silicone.
And just some mechanical properties…
This is a myoelectric prosthesis, which means it uses electrical sensors to detect contractions in the selected muscles of the residual limb. These contractions are than translated into movement of the bionic hand by a specific algorithms.
Luka: Ok, so which is better? Let’s start with transplantations of the hand. We will focus mainly on the hand, since leg prosthetics are nearly perfect, but with hand it’s different. You have many small and fine movements that are incorporated in every day’s life and you simply cannot function without a hand.
Just some short history for the beginning. The first hand transplant was actually performed in Ecuador in 1964, but the patient suffered from transplant rejection after only two weeks. Then, there was basically a long period of nothing. Up until January 1999. The first successful hand transplantation. Now, you should notice, we are talking about transplantation, not about replantation. The first successful replantation was performed in Shanghai, China, in January 1963.
So, in January 1999 the first person (a baseball player) underwent an operation. This kind of operation is probably one of the longest there is. It takes approximately 12 to 16 hours. In comparison, a typical heart transplant takes 6 to 8 hours and a liver transplant, 8 to 12 hours.
Hand transplantation is an extremely complex procedure, but may not be as difficult as a hand replantation in that a replantation usually involves crushed or mangled bones, tendons, and ligaments.
Barbara: Would you care to elaborate on how this is done?
Luka: Yeah, sure. In theory it’s actually quite straight forward. How this is performed is shown on the video behind. The surgeon will progress with tissue repair in the following order: first the flow of blood is restricted by a special trinket. Incision is then made to expose the deeper structures. Then the radius and ulna bones are fixated with metal plates. Then tendons are attached and repaired. By pulling the tendon, the fingers are flexed and therefore tested before they are reconnected. The same process in used to attach the extensor tendons. Then we start using the microscope and reconnect the nerves, by suturing them together. After the nerves have been repaired, next step is to ligate the arteries. Once we achieve anastomosis of both, radial and ulnar arteries, the hand is once again pronated to ligate the veins. Now the trinket is released and the surgical team watches the hand to become pink with the return of the circulation and the pulsation of the arteries is observed. And the last step is to close the skin.
Barbara: Ok, khm.. First of all, we must keep in mind that not all the amputees are suitable for hand transplatation, it is performed only in healthy individuals with normal life expectancy. And even if the procedure itself goes well, the rehabilitation process is long and complex, you know that whole team of medical support needs to be included.
Luka: Well, not really. It normally takes 6 weeks to stay in hospital. In the first week there is normally rest, but in the second week a man starts the rehabilitation. First passively and after the three, four weeks actively. And in six weeks you can go home.
Barbara: Now we’re coming to the most important point. Immunosuppressive medications.
Luka: Yes, probably the most important part of rehabilitation is immunosupression. Nowadays the therapy has much improved. The old fashioned option would be to use 3-regiment treatment with tacrolimus, mycophenolate mofetil and prednisolon. And the new way is to use steroid-sparing induction regimen with Alemtyzumab which is a humanized CD-52 monoclonal antibody, an effective depleting agent along with MMF and tacrolimus. But we lose the prednisolon. And before you start torturing me about rejections, I must admit, there are some rejection episodes. 85% of transplant patients had at least one acute rejection episode in the first year. But all of those episodes were easily managed with high-dose of iv. corticosteroids, mostly prednisolone, and all of those rejections were reversible, without any consequences.
Barbara: Ok, so there is a potential risk for acute and chronic rejections. And immunosuppressive medications work well, that’s nice. But, most important issue I see here, is that all immunosuppressive medications patient has to take for the rest of his life. We know that those have serious adverse effects, major ones being opportunistic diseases, than nephrotoxicity, cardiac damage, cancers. The patient has 5 times more chances to get a melanoma, 20 times more chances to get a small cell carcinoma (SCC), and 100 times more chances to get Kaposhi sarcoma, just to name a few. Don’t forget the compliance, which gives us additional problems. Not to mention there’s enormous psychological stress, for nobody can guarantee the patient will gain back sensation, and after all if rejection and ischemia occur, the patient is again on the start point. The transplanted hand is functionaly inferior and the restored sensory feeling is usually very weak.
Luka: Since you brought up the numbers. Let them speak for them selves. Hearth transplant has been here for ages. 1-year survival rate of the patients is around 85% or so, and around 75% after 3 years. On the other hand, we have a hand with a 1-2-year survival rate of 100%, and up until now, 95,6%. And you’ve also mentioned the loss of sensation… Motorics, within 5 years…practically normal. What is most important, they can perform everyday tasks. And sensorics; the return of protective sensation – 100%, the return of tactile sensation – 90%, and even discriminative sensation – 72%. Now the techniques and medications are getting better and better, therefore transplantations have better outcomes. As of March 2011, there have been a total of 70 hands transplanted on 52 patients around the world. It has been suggested that the risk-benefit ratio of human hand transplantation is similar to that of kidney transplantation because the immunosuppression protocols for hand transplantation are similar to those used in routine kidney transplantation.
Barbara: And of course there is additional problem with finding a cadaveric donor that suites patient’s sex, if it suites patient’s skin color, if it matches the size of patient’s hand.. There are just too many ifs. And look for the expenses, it takes around $758.000 based on 40-year life span, for unilateral transplantation, according to the AAOS (American Association of Orthopedic Surgeons). Now after all that I’ve pointed out, bionic hand is more reliable. Until 2007, prosthetic hand didn’t have the ability to move every digit separately. Than came i-Limb Ultra revolution. The bionic hand with 360° rotable wrist and thumb. The patient can smoothly control bending each finger separately, he can even gradually increase strength of its grip, and have access to 24 different grip patterns via App Store. It comes with warranty list, so if everything isn’t working perfectly, there are mechanics to repair it, it is replaceable, and unlike the transplanted hand bionic hand obviously isn’t receptive for ischemia.
Here is the guy with i-Limb Ultra:
And here we can see the patient can even tie his shoes with bionic hand.
Now let me introduce you to the one of the newest studies I was absolutely fascinated with, the project: LifeHand 2. Just a couple of weeks ago in Italy, a research team from different countries developed the prototype of the very first bionic prosthesis with restored sensation. The patient was able to feel the shape and the consistency of the objects he picked up and even detect the strength of his grasp, as we can see on the video behind.
Luka: Yes, all of this is fair and interesting and right now I am convinced; I want one of those. But tell me something… Where do I get such a nice prosthesis? In order to acquire one, you either have to be extremely lucky or you have to have plenty of money. We are again talking about $100.000+ for a relatively functional prosthesis, which is pretty much the same as transplantation. Most of the amputees still use traditional hook systems that haven’t really changed since 40s and it therefore doesn’t do much. All those new high-tech devices with so called “sensory system” you talked about, are pretty much like those limited edition sports cars. They make five of them and sell them expensively. For others those are out of reach.
Barbara: I knew you love numbers… Well, since the technology plays a big role in modernizing and improving, bionic hand is every step closer to the real human hand. And because it’s the matter of developing technology, prices dropped since the first i-Limb Ultra launched, so now it costs less than $100.000, around $60.000.
Luka: Now, let’s say, we can get a prosthesis ranked somewhere in between. The disadvantages of such a low-budget prosthetic hand would include for example weight. Normally those are heavier due to materials they are build from. Do not forget, they need some kind of power supply for them to function. And these batteries should last long, not that you have to charge them every day. Also keep in mind, that these are non-biological materials used and can therefore not regenerate as a biological tissue would. So they are susceptible to the environment and in need for frequent repairs. Other important obstacle is also compatibility of biological tissue with non-biological elements.
Last but not least, there is another consequential obstacle; lack of feedback and control. Robotic arms have no stereognosis, meaning they have no ability to know where the limb is in space, which would allow use of the arm in the dark, for example. A robotic arm is, after all, an adjustment, and for many it requires a shift in self-image, control, and expectations.
Barbara: Since the technology plays a big role in modernizing and improving, bionic prostheses are every step closer to the biological system. Because it’s the matter of a developing technology, prices drop since the first i-Limb Ultra launched, so now it costs less than $100,000. The investments in this field are enormous. The technology of materials is moving toward lighter ones, longer battery lives, different covers for the prostheses (with different shades, veins relief, hairs, polished nails, …), and most important investments in algorithms and techniques for sensory feedback. Till the end of this month we expect one more publish from the research center in Rome, regarding further improvements on Lifehand 2.
And as I promised – drummer with myoelectric prosthesis, what do you say?
Luka: Ok, after all our major points have been presented and since we are short in time, we would skip the conclusion, and rather ask you the same question, we’ve asked you in the beginning.
So, which would you choose now, if you lost your hand, for instance? Would you go with hand transplantation, or would you choose a nice, expensive bionic prosthesis?
I feel like, I’ve lost this debate. It looks like the great majority is still for bionics. So, all in all…
Barbara: Our topic today is both, depressing and paradoxically inspiring. But again, it is important to know that robotic arms and transplantation procedures are not suitable for all patients; plastic surgeons and psychiatrists must consider the patient’s goals, intelligence, maturity, motivation, and physical constraints, such as strength, dexterity, joint mobility, stump quality, and pain management. Both sides are on good way, immunosuppression gets less toxic, there are stem cells researches, new studies in bionics, every day we hear about new 3D printing utility. Who knows what the future brings?
Luka: Yes, who knows…