Bionic leg can read thoughts

Zac Vawter, 32, operates his leg with his brain, like anyone else. His leg is a "marvel of 21st century engineering," however.

Vawter is the "test pilot" for a new bionic leg -- the first of its kind to communicate with the brain. Arm prosthetics have been programmed as such before, but never before have leg prosthetics provided the same type of mobility.

The leg uses sensors to harness "reinnervated" nerves: Rather than allowing the nerves to die, they were surgically "rewired" to control his right thigh muscles.

The bionic leg is accordingly programmed to read the contractions of those muscles, giving him a near-normal gait not possible with current prosthetics.

The comparison to his other prosthesis is "night and day," Vawter said.

The error rate is down, from 12.9% with a robotic leg, down to just 1.8 percent for errors including trips and falls. The leg weighs about 10 pounds and was created by the Rehabilitation Institute of Chicago, which saw an $8 million boost from the US Army.

The Army hopes the leg will benefit more than 1,200 Iraq and Afghanistan veterans currently using traditional prosthetics.

Beyond veterans, 1 million Americans that live without lower limbs could be affected by the technology.

"The value it will provide to the people who use it will be enormous," the study's lead author said. "We are making fantastic progress."

The prosthetics should be available for widespread use in three to five years.