Steve Austin was a U.S. astronaut who was gravely injured when his spacecraft crashed back to earth. He was rebuilt, almost from the ground up by government-approved experimental surgeries, giving him powerful prosthetics.
The “Six Million Dollar Man” first aired in 1973, starring Lee Majors, and it ran for five seasons. I remember that show, and I was amazed, as were millions of others, with what he could do with his prosthetic limbs and eyes.
Today’s prosthetics are getting closer and closer to that reality.
Companies have made enormous progress in both the aesthetics and functionality of prosthetics, which can be passive (more cosmetic than functional) or more involved. More real-looking artificial limbs can now be made using 3D printers. They’re a tremendous improvement from what was available only a few years back. There are also body-powered prosthetics, where the movements of the upper body, shoulder, and chest are captured and used to open or close an artificial hand.
My old roommate from medical school, Lt. Col. Don Reed Jr. (retired) saved many lives while serving in Iraq as a battlefield trauma surgeon, but many of those brave men and women would come home missing limbs. This is a problem war-faring humans have faced for millennia.
Prosthetics have been used for thousands of years, with evidence of use in the times of the ancient Egyptians, according to a 2007 article in ANZ Journal of Surgery.
The first known true prosthesis used as a rehabilitative tool was that of the ancient Greeks. In 484 B.C., a soldier cut off his leg to escape imprisonment and replaced it with a wooden prosthesis. He travelled 30 miles on his wooden leg before being captured and quickly decapitated.
Today’s prosthetics are taking on a whole new meaning. The older prosthetics were simple tools to help a person cope with the horrible loss of a particular function. With a prosthetic leg, one was able to stand. Later, with advances, one could walk. The current generation lets an amputee run. Just think of the former South African runner, Oscar Pistorius, and the use of the “blade” prosthesis. Those blades were developed by medical engineer Van Phillips. The blades store kinetic energy like a spring.
There’s now even a technique of using sensors capable of detecting nerve impulses so the amputee can activate the movement of the artificial limb using the same neural pathways they once used for their original limb. This is moving much closer to the kind of increased functionality proposed by science fiction, such as Geordi La Forge’s neural vision glasses in Star Trek the Next Generation. We’re still far away from the true implementation of the six million dollar man, but we get closer every year.
One of the great limitations of artificial hands is the inability to have tactile sensation, such as in grasping an egg. There are experiments now being done whereby electrodes are implanted into the amputees individual peripheral nerve endings and attached to the prosthetic digits, which “can produce graded, discrete sensations of touch or movement,” according to an article in IEEE Transactions on Neural Systems and Rehabilitation Engineering. This article describes the first evidence for direct neural feedback and direct neural control of a prosthetic arm.
These kinds of prosthetic arms are still experimental, extremely expensive, and not ready for common use.
Just recently, a device was developed that’s actually a tactile sensory “glove” that can be placed onto existing artificial limbs. This glove uses sound to let the wearer learn through what’s called sensory substitution. This device was presented at the Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) in 2021.
Another improvement in prosthetics is more superficial, but also important. More real-looking artificial limbs can now be made using 3D printers. They’re a tremendous improvement from what was available only a few years ago.
There’s also osseointegration, which is a surgical technique that allows the amputee to attach the prosthesis directly to the bone of the missing limb. Osseointegration has been approved and used in Europe for several years and only recently here in the United States.
Myoelectric prosthetics use electrical stimulations from the residual limb to control movement of the new artificial limb by contracting that muscle, which sends the electric impulse to a controller that then triggers tiny battery-powered motors to move digits or the wrist, for example.
TMR, or targeted muscle reinnervation, is a very complicated surgical procedure for high amputees. This surgery rewires the nerves that were used in the hand or fingers to adjacent muscles with the goal of allowing the user to have some “thought control” over their prosthesis. The true functionality of this surgery is still limited, but promising.
Mobius Bionics has gone one step further and developed the LUKE Arm for shoulder-level amputees. This device allows the user to reach above his or her head (which was unheard of before with prosthetics) and even use a power drill. This arm uses a foot control placed on the shoe and intuitively reads the tilt of the shoe to interpret each movement and control the arm functions.
The future for artificial limbs is mind-boggling. I haven’t even touched on the ability of a quadriplegic (paralyzed from the neck down) to move a computer cursor with just thought or the “glasses” that will help a blind person “see.” Advanced technology, when used right, is amazing to witness, but we always have to be vigilant. The sad reality is that with every advance comes tremendous risk. The ability to better meld man and machine raises the possibility of far darker visions than the hopeful sights of the six million dollar man.
As Albert Einstein observed, “It has become appallingly obvious that our technology has exceeded our humanity.”