Three men have become the first patients in the world to have hands replaced by bionic versions controlled by their mind.
All had suffered nerve damage from accidental climbing and motorcycle injuries that left them with little control over their “real” hands and in pain.
The Austrian trio underwent a new technique called “bionic reconstruction” that involved amputating the hand and substituting it with an advanced robotic prosthesis.
Three months later, all three have for the first time since their accidents been able to accomplish everyday tasks such as picking up a ball, pouring water from a jug, using a key, cutting food with a knife, and undoing buttons. They are also said to be in less pain.
The bionic hand responds to “thought-controlled” electrical impulses from attached muscles.
Prof Oska Aszmann, director of the Christian Doppler Laboratory for Restoration of Extremity Function at the Medical University of Vienna, who developed the technique, said the "brachial plexus avulsion" nerve injuries suffered by the men in effect amounted to "an inner amputation".
He said: “Existing surgical techniques for such injuries are crude and ineffective and result in poor hand function.
“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.”
All three patients spent an average of nine months before amputation undergoing mental training to learn how to control a computer-generated “virtual” hand.
Once they they had mastered the virtual environment, they practised using a hybrid hand — a prosthesis attached to a splint-like device fixed to their non-functioning hand.
Details of the procedure are published in The Lancet medical journal.
Brachial plexus injuries occur when a network of nerves that originate in the neck region and control movement and sensation in the upper limbs, including the shoulder, arm, forearm and hand, are damaged.
They are often the result of trauma from high-speed collisions, especially in motorcycle accidents, and full-contact sports such as rugby.
In a linked comment in the journal, Prof Simon Kay, who carried out the UK's first hand transplant, and plastic surgeon Daniel Wilks from Leeds Teaching Hospitals NHS Trust, wrote: "The present findings, and others, are encouraging, because this approach provides additional neural inputs into prosthetic systems that otherwise would not exist.
“However, the final verdict will depend on long-term outcomes, which should include assessment of in what circumstances and for what proportion of their day patients wear and use their prostheses.
“Compliance declines with time for all prostheses, and motorised prostheses are heavy, need power, and are often noisy, as well as demanding skilled repair when damaged.”