• Posted July 12, 2023

B 7/12 -- New Bionic Hand Implant Allows Control of All Fingers

A multinational team of engineers and surgeons has developed a bionic hand with a high level of function in every finger -- a significant advance for amputees.

The team, from the United States, Sweden, Australia and Italy, developed a way to reconfigure what remains of a patient's limb. Then, they integrated sensors and a skeletal implant to connect with a prosthesis both electrically and mechanically.

By dissecting peripheral nerves and redistributing them to new muscle targets, the bionic limb can access much more information and the user can command many robotic joints at will, researchers said.

"We show that rewiring nerves to different muscle targets in a distributed and concurrent manner is not only possible but also conducive to improved prosthetic control,"said Max Ortiz Catalan, founding director of the Center for Bionics and Pain Research (CBPR) and professor of bionics at Chalmers University of Technology, both in Sweden.

"A key feature of our work is that we have the possibility to clinically implement more refine(d) surgical procedures and embed sensors in the neuromuscular constructs at the time of the surgery, which we then connect to the electronic system of the prosthesis via an osseointegrated interface," he said in a university news release. "A.I. algorithms take care of the rest."

While prosthetic limbs are most often used to replace a lost extremity, they are often hard to control. Movement may also be limited.

Because patients can contract muscles at will, another option is to use remaining muscles in the residual limb to control bionic hands. This generates electrical activity that can tell the prosthetic hand what to do, such as to open or close.

But when the amputation is at a higher level, such as above the elbow, not many muscles are available to do this.

Prosthetic limbs are commonly attached by a socket that compresses the remaining limb. This can cause discomfort and is mechanically unstable.

An alternative is to use a titanium implant in the residual bone. The study said this skeletal attachment allows for more comfortable and efficient mechanical connection of the prosthesis to the body.

The patient was able to control every finger of this new bionic hand as if it were his own, researchers said.

"It is rewarding to see that our cutting-edge surgical and engineering innovation can provide such a high level of functionality for an individual with an arm amputation,"said Dr. Rickard Brånemark, research affiliate at Massachusetts Institute of Technology and associate professor at Gothenburg University in Sweden.

The surgery was done at Sahlgrenska University Hospital in Sweden by Dr. Paolo Sassu, who previously led the first hand transplant performed in Scandinavia.

"The incredible journey we have undertaken together with the bionic engineers at CBPR has allowed us to combine new microsurgical techniques with sophisticated implanted electrodes that provide single-finger control of a prosthetic arm as well as sensory feedback,"said Sassu, now of the Istituto Ortopedico Rizzoli in Italy. "Patients who have suffered from an arm amputation might now see a brighter future."

Results were reported July 12 in Science Translational Medicine.

More information

The U.S. National Institutes of Health has more on prosthetics over time.

SOURCE: Chalmers University of Technology, news release, July 12, 2023