A man missing his lower leg has gained precise control over a prosthetic limb just by thinking about moving it — all because his unused nerves were preserved during the amputation and rerouted to his thigh, where they can be used to communicate with a robotic leg.

The man can now seamlessly switch from walking on level ground to climbing stairs, and he can even kick a ball around.

During a traditional limb amputation, the main sensory nerves are severed and lose their function. In 2006, Todd Kuiken and his colleagues at the Rehabilitation Institute of Chicago realized they could preserve some of that functionality by carefully rerouting sensory nerves during an amputation and attaching them to another part of the body.

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.

Kuiken’s team has performed TMR for the first time on a man with a leg amputation.