The Uphill Climb to Better Prosthetics

GeekMom Technology

Eight years ago I made the decision to have my left foot cut off. After years of struggling with a deformed foot, related to a mild form of Spina Bifida, I suspected that prosthetics might give me a more active life. I have not been disappointed.

Photo: Ossur

As technology continues to improve I won’t be the only person you hear about who’s chosen to be an elective amputee. More and more people are realizing that facing a lifetime of pain and immobility from injuries that failed to heal or chronically impaired limbs doesn’t make sense, when there’s a chance that life could be improved with the assistance of prosthetics.

But there’s one big factor that has to be considered. Replacing limbs is not an equal equation when you factor in which limb needs to be replicated. Arms and fingers are very different from legs and feet.

My kids have grown up with a mom who uses a prosthetic leg to get around. Metal feet are a normal thing in our house. They’ve also grown up discussing things that might not come up around the average dinner table. More than once we’ve mulled over the phrase they’ve heard me say many, many times: “I’d much rather lose two feet than just one hand.” It’s like a twisted version of the card game we play on road trips called “Would You Rather.”

And here is why I stand behind my beliefs. Ankles and fingers both have very intricate joints. Both do amazing things and have incredible range of motion. But in everyday life, one is much harder to replicate than the other.

After receiving my newest issue of Wired magazine in the mail yesterday, I looked forward to bedtime, anxious to dive into one of my favorite periodicals. I have a subscription for the teenage boys in my house, but somehow I find myself devouring the articles before I even let them know the new issue has arrived.

To my delight, there was an in-depth article about prosthetics. Of course I immediately flipped to it. It turned out to be a great article. If you don’t have your own subscription you’ll have to wait for the current one to hit newsstands, or for the article to be posted online, but in the meantime let me tell you, in a nutshell, what it said. Hands and fingers are just hard to replicate. Really hard.

When the Iraq war started almost a decade ago, and more soldiers started coming home with missing limbs, the military started throwing money at the field of prosthetic research and development. Goals were set and anticipation was high, considering the success they’d been having with teaching monkeys to control electric arms with their brains. But now deadlines have passed and goals have not been met, although not for a lack of trying. But it turns out that there’s  a lot about biology and the brain that we still don’t know. Simple things, like how the brain tells your fingers to do simple tasks like opening a pickle jar and tying your shoes.

Think about the range of motion your fingers use to do the tasks you’ve asked of them in the past hour alone. Have you poured a cup of coffee? Have you typed out pages of text on a computer? Have you changed the station on the radio in your car, while simultaneously turning on your left turn blinker and steering your car through a turn? Did you button a shirt, tuck in a shirt tail, brush your teeth, and comb your hair…all without really giving your fingers a second thought?

People with missing arms and hands envy you.

The monkey who fed himself marshmallows by using his mind to move the electric arm seemed like a promising step. But through this experiment we also learned that the place in his brain that sent the signal could change on a daily basis. There wasn’t just one spot to tap into to trigger arm movement. Beyond that, the electrodes placed on his head were not stable. Enclosed in his body cage they stayed on relatively well, but a normal person, walking around in the world, would dislodge the same kinds of electrodes before they left the house in the morning.

The way our arms and hands work together to seamlessly do the tasks we ask of them without giving it much conscious thought at all is much more complicated than we had previously thought. It’s not an issue of finding the one sweet spot in our brain to tap into.

But let me take you back to my own prosthetic limb. The leg I click on every morning with my own handy fingers has a metal foot attached to it. In that foot you’ll find some very strategic metal parts that do a fine job replicating the motion of basic gait. The day I clicked on my first leg, I acquired range of motion I never had with my withered old foot, and energy return to boot. My foot responds to the forward motion of stepping, and pushes off in return. It doesn’t really matter that in my everyday life  I can’t do ankle rotations. All I really need is forward motion, and some basic energy return.

Prosthetic Cheetah Legs

If I choose to become a serious runner, I have other options. Most people have seen pictures of the cheetah leg that amputee runners use, that replicate the running gait even better than a metal foot can. There is no equivalent when it comes to hands and fingers.

Even amputees who have lost a knee joint can find more accurate limb replacement than an upper limb amputee. A knee is complicated, but the requirements for everyday use are pretty basic. Working out details like having good range of motion while also being able to be stationary when needed, are issues that prosthetists and their patients work hard on, but the technology is good, and comes pretty close to getting the average person back to an active life.

One of my former prosthetists sent me a link this week, to a news story circulating in Great Britain. A woman who lost the use of her hand in an automobile accident, and has become tired of dragging around a useless limb, is lobbying to have it cut off, so she can take advantage of prosthetic technology. It’s a familiar story to me. I totally understand her reasoning. And I’ve seen many stories of upper arm amputees who are pleased with their prosthetics, including this upbeat young man, who has become pretty proficient with his electric arm.

I have no doubt this woman will gain something by having her hand removed. Even if she gets to a point of only having a basic open and close motion with her metal hand, it will be more than she had before the surgery. But it won’t be an easy road. As smart as our scientists are, and as much as we understand about how the world works, and how our bodies work, there is a vast amount of information still to discover.

Trust me, you’ll be seeing more and more stories online and in the news, about how the field of prosthetics has become state of the art. And it has. But also remember that the basic tasks you do on a daily basis, with your flesh and bone limbs, are not easy to replicate. Every small victory is a big one, when you live without a limb, and every step technology takes forward is a mountain to be scaled, to those of us living with bionics.

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