Artificial limbs in the high tech age
Published: 04 Aug 2005 15:35 BST
What percentage of that 1.2m amputees would go high tech, would have devices like the C-Leg?
In total, it's probably less than 10 percent of the population that would receive high-tech componentry. To give you an example, the C-Leg in the United States is a product that is generally recommended for mid- to high-active patients, and there are only about 8,000 of those a year that would be an above-the-knee, active amputee.
And we are taking about products that, from what I've read, are in the $40,000 to $60,000 price range?
That's a bit misleading. The products themselves are only a percentage of that. A $40,000 device would include all the components; the socket, which has the interface between the residual [limb] and the componentry; and the prosthetist's time. They can be that expensive, but it's a part of a total package.
Are we still in the first generation, or we are in a second generation of chip-based technology for the prosthetics?
As far as lower extremity is concerned, we're moving into the second generation. Now in upper extremity, which doesn't get a lot of press... myoelectric upper-extremity componentry has been around a long time. While (those devices) didn't use chip technology, they did use micro motors and batteries and power supplies and electrodes, so that was kind of a frontrunner. Actually, upper extremity really started the whole high-tech push.
How have the chips altered the design and use of the products?
Much like just about anything else where chip technology is applied today, it's basically making decisions faster. In this case what chip technology has allowed us to do is... very quickly monitor the terrain and the speed of the wearer and make adjustments, so that in essence the patient is in a much safer mode. Prior to chip technology, just to go down the stairs, typically an amputee takes one step at a time, and it would be good leg first and then they'd drag the prosthetic device behind them. With chip technology, an amputee goes down the steps one foot after another much like you or I would. The decision process is taken out of it [for the amputee], and it's made in the leg itself.
What are the limitations of something like the C-Leg and these higher-end devices? How reliable are they, what is their life span?
I don't think that the technology has a limitation. I think it's cost-return, cost-benefit that's the limiter at this point, because again we are not producing that many units. It's not like we're making mobile phones or calculators where you just continue to drop the price down because of volume.
What's the next big step?
The next big step is probably going to be motorised or power-assist [additions]. Today you're under your own power — there's a battery that drives the electronics, but it's your leg that powers the movement of the device. In the future there's some technology around 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?
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.
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