A Swedish truck driver has received a new type of prostheses connected directly to his nerves

Nerve-connected robo-arm passes first trial

A Swedish truck driver who lost his arm ten years ago has become the first person in the world to receive a robotic prosthesis connected directly to his nerves.

A major improvement compared to previously used artificial limbs controlled via electrodes attached to the patient’s skin, the robo-arm is connected to the patient’s body via a bone-anchored neuromuscular interface which transmits signals between the brain and the artificial limb.

The patient has been living with the innovative prostheses since January 2013. The technology and the patient’s progress have been detailed in the latest issue of the Science Translational Medicine journal.

“We have used osseointegration (bone-integration) to create a long-term stable fusion between man and machine, where we have integrated them at different levels,” said Max Ortiz Catalan, research scientist at Chalmers University of Technology, Sweden, and leading author of the publication

“The artificial arm is directly attached to the skeleton, thus providing mechanical stability. Then the human’s biological control system, that is nerves and muscles, is also interfaced to the machine’s control system via neuromuscular electrodes. This creates an intimate union between the body and the machine; between biology and mechatronics.”

The patient has reported improved levels of control over his artificial arm, even being able to tie his children’s skates, operating machinery or unpacking eggs.

“Going beyond the lab to allow the patient to face real-world challenges is the main contribution of this work,” Catalan said. “We see this technology as an important step towards more natural control of artificial limbs.”

The researchers hope that as the robo-arm’s neuromuscular interface was designed to be bi-directional, the patient could eventually be able not only to send commands from his brain to the arm, but also receive sensual impulses from the prosthesis.

“Reliable communication between the prosthesis and the body has been the missing link for the clinical implementation of neural control and sensory feedback, and this is now in place,” said Max Ortiz Catalan. “So far we have shown that the patient has a long-term stable ability to perceive touch in different locations in the missing hand.”

Intuitive sensory feedback and control are crucial for interacting with the environment, for example to reliably hold an object despite disturbances or uncertainty.

“Today, no patient walks around with a prosthesis that provides such information, but we are working towards changing that in a very short term,” Catalan said.

“We see this technology as an important step towards more natural control of artificial limbs. It is the missing link for allowing sophisticated neural interfaces to control sophisticated prostheses. So far, this has only been possible in short experiments within controlled environments.”

The challenging surgery connecting the prosthesis to the bone and the neuromuscular system was performed by associate professor Rickard Brånemark and his colleagues at Sahlgrenska University Hospital in Sweden.

The study promises a major breakthrough in prosthetic technology, which would be welcome by patients around the world.

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