WEDNESDAY, Oct. 14, 2009 (HealthDay News) -- Researchers say they're making progress toward better connections between prosthetic hands and the brain, potentially paving the way for amputees to do such things as type, sense hot and cold, and touch others.
If new strategies under development work in humans, they "would allow people to have a prosthetic that functions like a normal hand and provides sensory feedback," said Dr. Paul S. Cederna, one of the principal investigators behind the research.
In addition, he said, the research could do the same thing for prosthetic legs.
For the moment, however, it's unclear whether the new findings will translate from rodents, which have undergone testing, to humans. Still, researchers are hopeful. But for now, prosthetic hands continue to have severe limitations.
"The majority of the issues around new high-tech prosthetics are regarding the ability to control the prosthetic and the ability to get feedback from the prosthetic," said Cederna, a plastic and reconstructive surgeon at the University of Michigan Health Systems and an associate professor of surgery at the university's medical school.
People are able to carry heavy items and push things around, he said. But fine motor skills, such as the ability to type, remain elusive, as does the ability to move individual fingers.
The nerves at the end of the stump where an amputation took place are key, he explained. The brain still controls the nerves, which still carry signals. There's just no hand for the brain to talk to.
"If we can harvest those signals out of the nerve and feed them to the prosthetics, we'd be able to have the brain control the function of the prosthesis," Cederna said.
One approach uses tiny cuffs that wrap around nerves and pick up electrical signals. But the cuffs stop working over time, Cederna noted. Another approach that relies on a needle probe passed into a nerve suffers from the same problem, he said.
In findings to be released Oct. 14 at the annual Clinical Congress of the American College of Surgeons, Cederna and colleagues report that they developed a kind of junction that nerve fibers grow into. This allows a connection between the prosthesis and the brain.
"From our research we've done so far, it's working fantastically in a rat model, and we have good long-term stability," Cederna said. If it passes tests in humans, "it would work anywhere where we want sensory feedback," he said.
The potential cost of the approach in humans remains unclear, he said.
Researchers hope to test their strategy in people in three years.
Dr. Gerald E. Loeb, a professor of biomedical engineering at the University of Southern California, said the new approach could be an advance, but questions remain about how many signals can be transmitted between brain and hand.
The U.S. Department of Defense and the Army have funded the new research with $4.5 million. Many soldiers from Iraq and Afghanistan are returning to the United States with amputations.
The American Society for Surgery of the Hand has more on prosthetics.