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This guy had his hand amputated and replaced with a bionic limb

(The Lancet, Aszmann et al)

Three men have become the first to receive bionic hands through a new method designed to give greater muscle control with prosthetics that they can move just by thinking.

The big innovation was that during surgery, before removing their existing, injured hands, doctors implanted muscles to connect to nerves and help direct the prosthetic.

The bionic reconstruction technique was developed by researchers in Austria and Germany and published in The Lancet this week.

Watch as one of the patients attempts different tasks — first he uses his own injured hand, then a prosthetic attached to his arm. Finally, he tries to do the same exercises with his new bionic hand.

(The Lancet, Aszmann et al.)

Transplanting muscle into the forearm was a key step

The innovation with this particular method isn't the prosthetic itself, but the surgical technique and rehabilitation process. (The process is designed so that it can also be used with many existing electric prostheses. And there have been many developed in recent years, like the military-funded DARPA hand that someone even used for rock climbing.)

The three men had nerve injuries from accidents, and their hands had been almost completely functionless for years. All had nerve damage in the brachial plexus, a network of nerves that help control movement and sensation in the arm, shoulder, and hand.

The study was prompted by a lack of surgical techniques to bring back hand function in patients with injuries like these. Because of the complexity of the nerves that control the hand, past surgeries involving bionic prosthetics haven't always been successful.

In two of the three patients, there was only one muscle signal in the damaged forearm, which meant that the signal wasn't strong enough to control a prosthetic. So to give patients an additional signal, doctors took a muscle from the patient's thigh, transplanted it to his forearm, and connected it to intact nerves.

After that, the patients underwent about nine months of training to teach the brain a new way to move muscles in the hand. Then patients learned to control a virtual hand on a computer screen and a prosthetic hand that wasn't yet surgically attached.

Then the patients had their hands amputated, and after that, doctors attached a prosthetic that can senses electrical impulses in the forearm muscles and translate them into the prosthetic's movement of the hand.

"We have altered the biological landscape to interface with the technical aspects of the prostheses," says Dr. Aidan Roche, a surgeon and scientist at the Medical University of Vienna who helped lead the project. The project was conceived by the report's lead author, Professor Oskar Aszmann.

Will it improve people's lives over the longterm?

So far, the bionic hands seem to be working well. Three months out, the patients said they had substantially improved function in their hands, less pain, and a better quality of life. But the long-term effectiveness of the bionic hand isn't yet known.

"Motorised prostheses are heavy, need power, and are often noisy, as well as demanding skilled repair when damaged," says Dr. Simon Kay of Leeds Teaching Hospitals, who carried out the UK's first hand transplant and wrote an editorial accompanying the report.

And people with electronic prosthetics still face many of the same problems as people with other types of prosthetics — like trouble getting an artificial limb to fit just right and difficulty going through airport security.

"The final verdict will depend on long-term outcomes," he says, "which should include assessment of in what circumstances and for what proportion of their day patients wear and use their prostheses."

Update: Additional information was added about the researchers involved.