Researchers implant brain-controlled prosthetic arm with sensation

Researchers have developed the first robotic prosthetic controlled by implanted neuromuscular interfaces.--Courtesy of Chalmers University of Technology

A robotic prosthetic controlled by implanted neuromuscular interfaces has been demonstrated to be clinically successful in a patient for the first time. The researchers expect to treat more patients with novel technology this year. The results are reported in the latest issue of Science Translational Medicine.

The patient, a Swedish truck driver, was the first person to ever receive a prosthesis in direct connection to bone, nerves and muscle in January 2013. Dubbed an osseointegrated (or bone-anchored) implant system, it responds to the body's impulses via neuromuscular electrodes.

Prior to the surgery, the patient had a robotic prosthesis that was controlled by electrodes placed on the skin. But these systems have limited and unreliable functionality and patients typically reject them, according to the scientists. This patient's arm was amputated more than 10 years ago.

The patient has also been able to achieve long-term sensation via the prosthesis. This is accomplished through the implant's bidirectional interface. So, not only can the patient control the prosthesis through the implant, but he can feel it as well.

"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," Max Ortiz Catalan, a research scientist at Sweden's Chalmers University of Technology and lead author of the publication, said in a statement.

"Today, no patient walks around with a prosthesis that provides such information, but we are working towards changing that in the very short term," he added.

Unlike prior experiments that were only short term, this patient achieved long-term, stable ability to perceive touch through the prosthesis.

"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," Ortiz concluded.

The patient has sufficient functionality for the heavy duty tasks required at his work, but can also handle more delicate operations such as retrieving eggs from a carton or tying his children's skates, the researchers said.

The technology requires that a titanium implant be surgically inserted into the bone and fixated to it through bone ossification over time. An abutment is then attached to the implant and the prosthesis is attached to it. Electrodes are surgically implanted in nerves and muscles to control the prosthetic system. These electrodes receive signals that are sent via the osseointegrated implant to the prosthesis, then the signals are converted into motions.

Hundreds of patients have received osseointegrated prostheses, but this technology goes further by enabling neuromuscular control.

- here are the release and the paper (sub. req.)