Wounded warriors at Walter Reed National Military Medical Center recently used a new prosthetic arm that they can control with their thoughts.
The arm was developed as part of a four-year program by the medical center, Johns Hopkins University Applied Physics Laboratory, and Uniformed Services University of the Health Sciences. It weighs 9 pounds, has as much dexterity as a human limb with 22 degrees of motion and allows users to move fingers independently of one another.
The nerves along the spinal cord continue to function in an amputee and still connect to some arm muscles. The idea behind the prosthetic is to pick up electrical signals from the muscles that still exist under the skin and convert them to a computer signal that will drive a robotic limb. Amputees go through training in a virtual environment to capture their muscle movements before being outfitted with the prosthetic.
“Normally when you move your hand, you think about moving your hand, and a signal comes down from your brain, goes down through your spinal cord, out through your limb and activates muscles in your hand to open or close,” said Army Col. Paul Pasquina, chief of orthopaedics and prosthetics at the medical center.
The hand, he said, is an important part of one’s independence. Highly functional and independent service members now struggling physically and emotionally with their impairments, the ability to dress, feed and groom themselves again, will help them regain a sense of self, he said.
Researchers are working to add a sense of touch to the arm. They are investigating using the same technology for prosthetic legs. Other efforts in this realm include putting electrical sensors directly on nerves or embedding them in the brain.
“I think there’s still a lot to be learned on how the human body can integrate with computers and computer interface, and I think the sky’s the limit in terms of what we will do over the next five to 10 years,” Pasquina said.