Bionic Limbs Promise to Improve an Amputee’s Quality of Life

By Earl Hunsinger

Back in the 1970’s there was a television show called the Six Million Dollar Man. It featured an astronaut who had lost both legs, an arm, and an eye in a terrible accident. If you grew up in that time period you can probably quote the opening narration: "Steve Austin, astronaut. A man barely alive. Gentlemen, we can rebuild him. We have the technology. We have the capability to build the world's first bionic man. Steve Austin will be that man. Better than he was before. Better, stronger, faster."

The premise of the show was that a government agency used advanced technology, or bionics, to "rebuild him" so that he could work for them as an agent. While that was an entertaining show, it was just fantasy, right?

Believe it or not, "we have the technology" today, or at least we almost have it. Bionics is a real science. It is defined by Webster’s dictionary as "the science of designing instruments or systems modeled after living organisms." This definition is broad enough that it includes things like basing the design for the hull of a boat on the skin of a dolphin, as well as sonar, Velcro, and a multitude of other "inventions."

What about prosthetic limbs? For hundreds of years amputees have made use of very simple artificial limbs, a peg leg or a hook hand. However in recent years, the science of prosthetics has seen some exciting new developments. Amputees have long known that at times their brain still thinks that a missing limb is still there. These are referred to as phantom limbs, and can often cause the amputee pain.

The good news is that if the brain thinks the limb is still there it is still sending out nerve impulses to try to control it. You might compare this to removing a light fixture in your house. The electricity is still there and the light switch still works, but of course nothing happens when the electricity gets to the where the fixture used to be because it has been removed. The solution in your house is to install a new light fixture. For a limb the task is similar, but quite a bit harder.

Researchers really have two tasks, designing better artificial limbs and figuring out how to tap into the "wires" that carry the control signals from the brain. How are they doing?

As described in the MSN article Double Amputee Uses Thought-Controlled Arm, a man who lost both arms in an accident is now testing a bionic arm that allows him to do chores around the house. The motion of this arm is much smoother than a regular prosthetic limb because it is controlled directly by the brain, in the same way that the original arm was.

What if the limbs are still there but the nerve impulses can no longer reach them, such as with spinal cord injuries? As the wired.com article Transforming Thoughts Into Deeds shows researchers are also now testing a brain-computer, or direct neural, interface that holds the promise of giving greater mobility to quadriplegic patients. This device works by directly "reading" neurons in the brain. Once these neurons are read, the signals can theoretically be used to control any mechanical or electronic device.

In addition, various researchers are working on bionic eyes, bionic ears, and so forth, not to mention the already successful artificial heart and the work being done on other artificial organs.

None of these has allowed anyone to be better, stronger, or faster than he was before, at least not yet. Still, the science is just getting started, and for someone who has been robbed of his once normal life, even the small benefits already being seen are certainly welcome.