The technique required the men to have their lower arms amputated and fitted with a robotic replacement which responds to electrical impulses when the muscles contract in the same way as a real hand.

“In effect, brachial plexus avulsion injuries represent an inner amputation, irreversibly separating the hand from neural control,” said Professor Oskar Aszmann, Director of the Christian Doppler Laboratory for Restoration of Extremity Function at the Medical University of Vienna, who pioneered the technique.

via Watch: Star Wars-style ‘bionic hand’ fitted to first patients – Telegraph.