Three men in Austria have each been implanted with the world's first bionic hands. The artificial hands are controlled by the mind of the user.

Bionic reconstruction involves the transfer of muscles and nerves, as well as replacement of damaged body parts with prosthetic devices.

The three patients suffered from damage to a network of nerves called the brachial plexus, from climbing and automobile accidents. These injuries act as an internal amputation, cutting hands off from nerve signals that would otherwise control them. Each of the recipients suffered for years from poor hand function following their incidents.

"The scientific advance here was that we were able to create and extract new neural signals via nerve transfers amplified by muscle transplantation. These signals were then decoded and translated into solid mechatronic hand function," Oskar Aszmann of the Medical University of Vienna said.

Prior to amputation, the patients each spent an average of nine months learning how to use their minds to control a virtual representation of the bionic hand. After those sessions, the subjects were fitted with a temporary hybrid hand, attached to their dysfunctional hands through a splint-like device.

After the bionic hands were implanted in patients, the subjects took part in physical rehabilitation to learn how to operate the devices. Within three months, each of the patients reported reduced pain, and the ability to use their hands to carry out everyday tasks, such as pouring drinks, cutting food, and using keys.

Brachial plexus injuries frequently occur in high-speed accidents, particularly motor cycle crashes. Estimates suggest that one in every 20 people involved in serious snowmobile and motorcycle accidents suffer from injuries to this region. That incidence could be as high as 26 percent among those people who play Canadian football. The nerves begin in the neck, and radiate out to shoulders, arms, and hands.

Numerous traditional surgeries were attempted on the patients, in order to try to repair nerve damage, but were unsuccessful, due to the level of damage in the structure.

"But still there are some nerve fibres present. The injury is so massive that there are only a few. This is just not enough to make the hand alive. They will never drive a hand, but they might drive a prosthetic hand," Aszmann said.

A segment of nerves from legs of the patients were transplanted into the shoulder area, in an effort to amplify signals from the brain. These were allowed to grow for three months prior to learning how to move the temporary hand.

Operations to implant bionic hands in the three Austrian men, and details of their recovery, were published in The Lancet.