Prosthetic hand brings old sensation back to amputee

Italian scientists have built a replacement hand for an amputee that can pick things up but also "feel" them. The patient had not experienced the sensation of touch for 10 years prior to this.

The sensations are rudimentary, for example being able to sense the difference between a sliotar and a mandarin. Even so the scientists from Switzerland and from Italy believe it shows what is possible and opens the way towards being able to sense other aspects such as temperature and texture.

Sensors in the hand were connected to remnant sensory nerve fibres in the stump of the amputated hand of Dennis Aabo Sørensen from Denmark. The sensors released an electrical signal that was picked up by the connected nerves and allowed him to sense the shape and stiffness of the objects he picked up. He was also able to distinguish this when blindfolded.

The prosthetic hand provided the patient with almost natural sensory feelings that matched those in his good hand, the researchers said, describing their work in the journal Science Translational Medicine.

He could increase or decrease the grasping force and this helped him to identify what he was holding. He had not felt these touch sensations since he lost his hand a decade ago, the researchers said. Nor did it take an exceptional amount of training to help him achieve the ability to recognise the feeling of other objects such as a bottle.

Ultra-fine electrodes were attached to the nerves and these in turn relayed the very weak electrical signals coming from the hand. Its success however provides the first step towards an actual bionic hand, although it would be years before it becomes commercially available, the researchers said.

Sørensen lost his left hand in an accident involving fireworks during a family holiday. Having experience such sensations for the first time in years, Sørensen must now get used to their loss as the hand is disconnected.

The researchers plan to do a pilot clinical study with more patients and will look at the long-term usability of this technology.