Sgt. James “Eddie” Wright is the only Iraq double-arm amputee to return to military service. Is he doing this with the help of new high-tech fully neuro-interfaced prosthetic arms? Nope: metal hooks. USA Today is running an article enumerating the problems with the current state of upper extremity prosthetics, along with the challenges facing those hoping to improve them.
“I remember when I first came back for rehabilitation, they were touting the myoelectric (battery-powered) hands as the greatest innovation. I was so disappointed,” Wright said, describing how the hooks are much easier because they don’t fall off his arm, are supple enough to “pick up a paper clip” and are much more reliable than battery-powered limbs.
Recognizing that the technology for hands and arms hasn’t improved significantly in the past six decades, the Defense Department is embarking on a multimillion-dollar research program to revolutionize upper-body prosthetics. Over the next four years, the Pentagon will fund development of what it hopes will be vastly improved artificial hands and arms that can be controlled by the central nervous system.
Artificial arms are much more difficult to design than artificial legs and have proved a harder sell to skeptical patients. Leg amputees typically need a prosthetic device to move around and are therefore more likely to use one. A single-arm amputee can often get along without a prosthetic. Adding motors and other materials needed for an easy-to-use artificial arm has been a huge challenge, said Weir, a researcher and artificial-hand designer at Northwestern University.
A typical adult human arm, Weir said, weighs about 5.5% of a person’s total body weight. So someone who weighs 170 pounds has arms that weigh more than 9 pounds each. But even a 6-pound artificial arm, he said, is too heavy for most to wear very long because it doesn’t have the support that a natural arm has.