Prosthetic Arm on 60 Minutes

On Sunday night, CBS' 60 Minutes did a really good, detailed report on the Revolutionizing Prosthetics 2009 project.

Scott Pelley interviewed most of the project's major players: among them Dean Kamen, who is responsible for one of the two arms; Col. Geoff Ling, the neuroscientist who conceived the whole program from whole cloth and made it a reality, and Jon Kuniholm, who wrote Spectrum's March feature on opening prosthetics design.

The problem is, of course there is only so much time on a segment-based one hour news magazine. So they didn't get to cover what I think is the most important part of the RP2009 project: the control mechanism.

Itâ''s also the most complicated so I donâ''t fault them for not wanting to get into the hairy details. However, I canâ''t overstate the fact that this is the single most important part of what makes Col. Lingâ''s project so revolutionary.

People have been working up new prosthetics designs for centuries. Around 1509, this medieval arm prosthesis was made for Goetz von Berlichingen. More recent versions are pretty fancy and delve into robotics.

They all look great, but they are inert. Even the ones with motorized fingers are window dressing. None of these accoutrements have gotten real amputees past their go-to: the sturdy old split hook design created before WWII. Itâ''s simple and basic, but it does the job. You know why? Because you can control it. You shrug your shoulder to open it, you shrug your shoulder to close it. The response is immediate and intuitive, if not very complex.

Myoelectric arms--which use electrodes to read muscle signals from the surface of the skin and use them to drive a mechanical arm--use a similar idea. The point is to make it as intuitive as possible to control the arm. You donâ''t want to have to relearn things that are counterintuitive.

And so, where Dean Kamen's arm is a miracle of compact, sophisticated engineering, the control mechanism they showed for it is kind of rough. You move the arm with your feet; kind of a joy stick control pad inside the shoes that you press to activate certain features.

Veterans Health Administration head of prosthetics Fred Downs, himself an amputee, demonstrated that after 10 hours he was able to use the interface remarkably well.

But still: with foot pedals controlling your arm, you wonâ''t be able to use the arm while youâ''re walking anywhere. Youâ''ll have to remember to turn it in and off if you want to go for a jog. And though it will become intuitive with repeated use, it's a learning process that is not inherently intuitive.

And that, ultimately, is what makes the RP2009 project so unlike its previous ancestors. It allows for control and feedback.

The 60 Minutes show touched on the control aspect briefly, showing Jon Kuniholm using electrodes to drive one of the prototype arms. But the electrodes aren't the point: the point is that the new technologies can interface directly with the muscles and the nerves. And thatâ''s whatâ''s cutting edge.

The Johns Hopkins University Applied Physics Lab, which was not mentioned in the program, and the Chicago Rehabilitation Institute, work on ways of integrating the arm into the human nervous system, so we can truly get to the Luke Skywalker arm: their research includes peripheral nerve implants and rice-grain sized implanatable lectrodes that will one day take over for the external electrodes in controlling the ICs that drive the robotic arm. Not to mention the brain machine interface.

The omission is understandable-- it's hard to boil something so abstract and engineery down to a few minutes. Still it was too bad not even to see a nod to the people who makes this project so mind-blowing, like Stuart Harshbarger and Todd Kuiken.

I am most glad though, that this project is getting mainstream attention. More people need to know about it, and getting it out of the prototype phase and onto amputees means it needs funding, and it needs to be visible to get funding.

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