According to the researchers, most prosthetics in use today were developed over a decade ago and have no motor control. The researchers will present the findings they have made in improving the function of prosthetic hands and possibly restore the sense of touch for injured patients at the 95th annual Clinical Congress of the American College of Surgeons.

The project is being funded by the Department of Defense and came from the need for improved prosthetic devices to improve the life of soldiers wounded in battle. Robotic prosthetics are already available for some uses and the goal of the researchers was to overcome the shortcomings in today's robotic devices. Namely, these shortcomings are the limited motor control and no sensory feedback.

"Most of these individuals are typically using a prosthesis design that was developed decades ago," says Paul S. Cederna, M.D., a plastic and reconstructive surgeon at U-M Health System and associate professor of surgery at the U-M Medical School. "This effort is to make a prosthesis that moves like a normal hand. There is a huge need for a better nerve interface to control the upper extremity prostheses."

The team of researchers created what they call an artificial neuromuscular junction that is made of muscle cells and a nano-sized polymer placed on a biological scaffold. The body has natural neuromuscular junctions, which are the point where nerves innervate muscle to form connections from the brain to the muscle.

The bioengineered scaffold was placed over the severed nerve endings like a sleeve. The researchers found that the muscle cells on the scaffold were able to bond to the body's native nerve sprouts and feed electrical impulses to the brain. The researchers are testing on lab rats right now. In animals, the researchers were able to get the scaffold to relay both motor and sensory electrical impulses and create a target for the nerve endings to grow. It is common for the body to grow an abnormal mass of nerve fibers at a point where they are cut.

"The polymer has the ability to pick up signals coming out of the nerve, and the nerve does not grow an abnormal mass of nerve fibers," explains Cederna.

In lab tests, rats were able to respond to the tickling of their feet with the appropriate signals to move the limb according to the researchers. If successful, the researchers will one-day move onto human trials and may be able to give those missing limbs back sensory input and mobility lost to accident and war.