Nerve rerouting helps man control prosthetic leg

With some careful nerve rerouting, scientists have allowed a man who had a body part amputated to almost seamlessly control a prosthetic replacement, using nothing else but his own thoughts.

Researchers at the Rehabilitation Institute of Chicago in Illinois pulled off the feat by rerouting sensory nerves during an amputation and attaching them to another body part.

"They could then use the rerouted nerve signals to control a robotic limb, allowing a person to control their prosthesis with the same nerves they originally used to control their real limb," NewScientist.com reported.

Initially, Todd Kuiken and his colleagues first tried the procedure dubbed targeted muscle re-innervation (TMR) on people who were having their arm amputated.

But the team recently performed a TMR for the first time on a man with a leg amputation.

The result? The man who lost his lower leg has gained control over a prosthetic limb, "just by thinking about moving it," NewScientist said.

It was because his unused nerves were preserved during the amputation and "rerouted" to his thigh, where they can communicate with a robotic leg.

With this, the man can "seamlessly" switch from walking to climbing stairs and can even kick a football around, the report added.

"I think this kind of work is very important," said Michael Goldfarb at Vanderbilt University in Nashville, Tennessee, who helped design the robot leg.

Goldfarb said that while there is much one can do with sensors on a prosthetic limb, electrical signals from the nerves "give you an extra set of information to work on."

Procedure

The team first rerouted the two main branches of the man's sciatic nerve to muscles in the thigh above the amputation.

"One branch controls the calf and some foot muscles, the other controls the muscle running down the outside leg and some more foot muscles," NewScientist.com said.

Some months after the procedure, the man has learned to control his thigh muscles by thinking about using his missing leg.

NewScientist said the robot leg used in the procedure is itself a sophisticated device, containing mechanical sensors including gyroscopes and accelerometers.

The leg can learn to use information from these sensors to perform certain walking styles.

Kuiken's team believe the leg could perform better with input from the sciatic nerve.

While the robotic leg made the correct movements using just its mechanical sensor data, the accuracy jumped to 98 percent with added information from the nerves.

Also, NewScientist.com said there were no "critical errors" that could risk the user losing balance and falling. — LBG, GMA News