High-tech prosthetic arm that blends with patient anatomy

Researchers say Thursday, April 30, 2020 (Health Day News) -The new “Mind Control” prosthesis arm allows amputees to regain tactile sensation and make daily life easier.

The success story involves only three patients in Sweden. But everything has lived with prostheses for 3 to 7 years. I use it for everything from work to skiing, canoeing and ice fishing.

Unlike traditional arm prostheses, which are uncomfortable and difficult to manipulate, the new ones are directly connected to bones, muscles and nerves in the rest of the natural arm.

In other words, according to Mr. Max Ortiz Catalan, a senior researcher who is an associate professor at the Charmers Institute of Technology in Gothenburg, Sweden, it can be operated more accurately.

However, the most radical advancement is that people can “feel” what they are touching.

Three patients (all men in their 40s) say they have a high degree of trust in their limbs and feel like “a part of themselves”.

US experts praised this work. New England Medical Journal.

Paul Marasco, director of the Cleveland Clinic Bionic Integration Laboratory, said there have been many advances in prosthetic technology in recent years. But he said it all had to be integrated into a prosthesis that people could easily use in their daily lives.

“What’s great about this study was that they used established technology and newer technology that had been studied and fused it all together,” Marasco said.

For one, traditionally, arm prostheses have been attached to the remaining extremities with a support system such as a “socket” and shoulder harness. However, it can cause knobs and irritation, and prostheses are usually cumbersome to operate.

The following video, narrated in both Swedish and English, highlights the various movements of the prosthetic arm.

The new prosthesis is attached using a recently developed technique called osseointegration. Here, the prosthesis is surgically fixed to the bones of the remaining arm.

From there, electrodes are embedded in the arm muscles and nerves. They serve to relay signals bidirectionally between the brain and the prosthesis. These signals are interpreted by a small control system embedded in the prosthesis using advanced artificial intelligence algorithms developed by the Swedish team.

As a result, people can control limb movements with their hearts. On the other side, an artificial thumb “force sensor” sends information to the brain so that it can perceive the pressure level on the hand.

“They’re thinking about opening their hands, they’re thinking about opening their prosthetic hands,” said Ortiz Catalan. “And when they touch an object, they feel a touch.”

Sophisticated “Myoden” arm prostheses are already out there. They are powered with the help of electrodes placed on the rest of the natural arm skin. The signal from the muscle is sent to an electric motor that operates the prosthesis.

“But this study takes it to another level,” said Dr. Robert Rosbrook, who is responsible for limb extension and complex reconstruction services at the New York City Special Surgery Hospital.

Rozbruch is one of the few US surgeons already using osseointegration to attach prostheses, including myoelectric prostheses.

The advantage of the new prostheses is that the electrical signals from the embedded system “look much stronger and you can get more out of them”.

“That’s amazing,” Rosbrook said, “so we can get both motors. [movement] And sensory information. “

Two of the three patients had phantom limb pain with an old prosthesis. This is a common phenomenon in amputated limbs, where the painful sensations are perceived to result from the absence of limbs.

After receiving the new prosthesis, both patients saw their pain disappear. Ortiz-Catalan says this is because the prosthesis uses the same neural network that “lost its job” due to amputation. They are “back to work” and are no longer dealing with pain.

At this time, this technology is only available in Sweden. According to Ortiz-Catalan, it is expected to become more widely available in the coming years. The researchers are also working on a similar leg prosthesis, which will be implanted in the first patient later this year.

Rozbruch said these early patients showed that this approach was feasible. However, he noted that wider use also depends on practical issues, including costs.

In terms of durability, Ortiz-Catalan said the ported system is expected to last a lifetime.

For more information

The National Library of Medicine Artificial limbs.