Professor Hubert Egger, M.D., of the University of Linz in northern Austria and amputee Wolfgang Ragger have made medical history. Together they invented and are demonstrating a leg prosthesis—believed to be the world’s first—that provides “feeling” for the amputee.
As Ragger said, “It’s like a second lease of life, like being reborn. It feels like I have a foot again. I no longer slip on ice and I can tell whether I walk on gravel, concrete, grass or sand. I can even feel small stones.” The 54-year-old former teacher cycles, goes climbing and his limp is barely noticeable, according to Nina Lamparski, the Medical Xpress writer who reported the story.
Egger developed the process in two stages. He first rewired the remaining foot nerve endings from Ragger’s stump to healthy tissue in his thigh placing the nerve endings close to the skin surface. He then fitted six sensors to the foot sole of a lightweight prosthesis, and linked them to stimulators inside the shaft where the stump sits.
“In a healthy foot, skin receptors carry out this function but they are obviously missing here. However, the information conductors—the nerves—are still present, they’re just not being stimulated, ” Egger said.
“The sensors tell the brain there is a foot and the wearer has the impression that it rolls off the ground when he walks. All things considered, the procedure is a very simple one given the results.”
Lamparski writes that this is not the first time the Austrian scientist has caused a stir with his research. In 2010, he presented a mind-controlled prosthetic arm, which the user directed with motor neurons previously connected to the lost limb. Egger explained that for the artificial leg the principle remains the same except that the process works in reverse: Information is passed from the prosthesis to the brain, rather than the other way around.
There was another benefit to the new prosthesis. Ragger became pain free. Within days of undergoing the operation he was no longer experiencing disabling pain. Egger points out that phantom pain occurs because the brain gets increasingly sensitive as it seeks information about the missing limb. The advantage of the “feeling prosthesis, ” he says, is that the brain once again receives real data and can stop its frantic search.
