Prosthetic hands you can control with your mind

It sounds like something from science fiction but it’s been announced that 3 Austrian men have had their non-functioning hands replaced with prosthetics that they can control just by thinking about it. The procedure, which doctors are calling “bionic reconstruction”, is unprecedented because it requires that the original hand is newly amputated. Currently prosthetics are generally used when part of a limb has been amputated sometime previously.

The men in question had all suffered injuries affecting the brachial plexus, which is the bundle of nerve fibres that run from the spine to the hand. They had lost almost all function in their hands as a result, with only a few nerve fibres still working. This was enough, however, for Professor Oskar Aszmann of the Medical University of Vienna to attempt his new procedure.

The first step was to graft some muscle from the leg into the injured arm, in order to boost the signal from the remaining nerve fibres. After 3 months had passed and the muscle and nerves had grown together, the men began training their brains. Initially they practised activating the muscle using a armband that detected the electrical activity. Then they learned how to control a virtual hand before a hybrid hand was attached to their own limb. After 9 months practice the men’s own hands were amputated and replaced with a robotic prosthetic that they were now trained to control using their muscles and remaining nerves.

Amputating the hand at the last minute means that the surgeon is able to decide where to sever the limb to provide maximum function and stability, rather than having to deal with problems caused by a traumatic amputation. These particular prosthetics are plugged in to mains electricity every night to charge, which means that all the muscles and nerves need to do is send the right signals to operate the hand; they don’t have to power it as well.

Milorad Marinkovic holds an egg with his new prosthetic hand (photo credit: Ronald Zak/AP)
Milorad Marinkovic holds an egg with his new prosthetic hand. (Image: Ronald Zak/AP)

All 3 patients have demonstrated vastly improved mobility and dexterity. On a test called the Southampton Hand Assessment Procedure, where a score of 100 represents a normally functioning hand, the men increased their average score from just 9 before the operation to 65 afterwards.  They are now able to grasp and throw a ball, pour liquids and fasten buttons. Of course, this increase in ability doesn’t include the sense of touch; there are around 70,000 nerve fibres connected to the hand and only 10% of them are to do with movement. But this procedure is still an incredible advance that gives hope to people who’ve suffered nerve damage.

 

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