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that will assist the patient, to actually in this case go upstairs, power its way up. That should be here in the next couple of years. To me the next step is to be able to connect to the neuromuscular areas of the body and actually have the body (use) the brain power of the device. Instead of having to think "I'm going to move my leg" and then move it, you just think and the nerves will fire and you'll move forward.
That's the myoelectric aspect, right?
Harman: Myoelectric is that way. The difference is, myoelectric (technology) uses an external electrode--when you flex a muscle you're powering the electrode, you're sending an electrical signal. In this case, we're talking about implants, where you're actually implanting the electrode, and wrap it around a nerve or wrap it around a particular part of the muscle and then have, either through radio frequency technology or some other technology, have that nerve speak to the device, and the device will move. I think that's 10 years away or less.
And there's osteointegration we've been playing with for a long time. There's a lot of headway being made there. Today a prosthetic device is attached to a socket--your residual limb is put into the socket. You could eventually see where you're actually attaching prosthetic devices directly to the bone, and if we can solve some of the issues associated with that, it will be a much more comfortable and probably more responsive prosthetic device.
What about some of the other materials--the plastics used for the skin, the titanium or whatever the metal is that is part of the frame?
Harman: Titanium has been around awhile. I think the one that we have adapted most recently that's really been successful is
There will be some other materials coming down the road, especially in the plastics area, but we haven't found anything as strong or light yet as a carbon fiber composite.
What about the skin?
Harman: I don't think there is a lot of fundamental research being done there...The future of having a more sensitive cosmesis, something that is more tactile, maybe has some sense to it or feel to it--there isn't a lot of work being done in that area. It's very, very expensive.
There were three parts to the technology question. I think I only covered the one, the limiting factor.
The reliability and the life span?
Harman: We're finding that with electronic and electronic-assist, with some of these new materials we're getting much longer life out of the limbs. A typical prosthesis, a hydraulic knee joint or standard knee joint and foot, might last about three years. With C-Leg--this is our sixth year in the United States, and we don't get that many back. Part of that has to do with the fact that materials are certainly that much better, but also these now require service intervals, where a traditional hydraulic knee joint and foot didn't require that at best. But with a C-Leg and the electronics that are associated with it, you get it back here once a year or once every two years, and the electronics and everything are just about rebuilt when you go back out again.
At a risk of using the wrong term, how close does the prosthetic get someone to being "normal," to having the equivalent of the arm and leg they were born with?
Harman: First of all you're never going to be normal. That's No. 1, and that's the first thing I think any prosthetist would tell an amputee--define "normal," I guess--but you're never going to be like you were. I think that the more we can give them or the more our products can take (out) the risk associated with been an amputee, take the decisions out of it, the closer we'll get to normal activities. An amputee can ride bicycles, can run, can swim. They can walk up and down stairs, they can walk up and down rough terrain with these devices, a lot easier. So rather than saying how normal would they get, I would say they could get much closer to normal everyday activities using these devices.
There were some reports a couple of weeks ago in the Australian press about a man who has just gotten what was described as the first "dynamic arm," an Otto Bock product. What is a dynamic arm? Is that a new product?
Harman: Yeah, it's a new product. All of our upper-extremity prosthetic devices had power-assist in the hands and wrists, so you could rotate through the wrist and you could open and close the hand, with myoelectric technology. The elbow was always a mechanical move--someone had to literally shift their weight to throw an elbow up or down, and lock it. The new technology is power-assist in that area, so it's basically moving up the arm with the technology.
Harman: I don't see anything like that, I think again because of the cost. When we talk about power assist or bionics, we are trying to get people back again as close to everyday activity as we can get them. I don't know of any work that's being done to make them superior to what they were. Now the military is working on a number of projects--and we're involved in that--to not make the soldier better, but get the soldier who has lost a limb back into combat, if that's what they choose to do, back into a more active military life. In the past, anyone who lost a limb in the military pretty much was discharged and they were then part of the VA system...But again it's not to make them superior, they're not going to run faster or shoot straighter or anything else. When we speak about bionics it's still all about normal activity.
Currently there is synthetic muscle that could afford a prosthetic limb more natural and a fuller range of movement (though they're not very strong yet), as well as power systems that can create electricity from sugar compounds like the glucose in the human bloodstream. Then theres the synthetic skin that was developed with dozens of tactile sensors per square inch that is still sitting on a shelf from 5 years ago. Also recently theres been breakthroughs in integrating systems with actual nerves in the motor center of the brain. Already there have been experiments where monkeys could actually feed themselves banannas with only a robotic arm controlled by thought.
But these areas of research cant even be considered yet in the prosthetics world and are only marginally being looked into in the world of robotics mainly because of lack of funding.
Its a bit of a catch-22 unfortunately. They cant afford cutting edge research because they dont make enough money off prosthetics sales to afford it. Out of a genuine desire to help people they raise the prices of the devices to fund research but the higher prices only results in reduced sales because the amputees cant afford it either.
If you really want to help this realm of research, do fund raisers and petition the government and companies to sponsor this research field which is struggling far behind where they could be today.
- by legs42 September 30, 2009 6:52 PM PDT
- I am located in West Sacramento,I am a bi-lateral amputee [both legs above the knee] I would be happy to assist any research program,I now have two c-legs[6 months].I have problems putting them on.my thighs have gotten larger since the last fitting.Please free to contact me if need be west sacto located in calif thank you William Schwab
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