Unprecedented control in each finger of a bionic hand thanks to a surgical breakthrough

Much progress in bionics toward the connection between living tissue and electronic hardware has been made from this last shore. Now, a remarkable advance from the first shore connects the two worlds much more intimately.

Prostheses are the most common solution to replace a lost limb. However, they are difficult to control and often unreliable, with only a couple of moves available. The muscles remaining in the stump are the preferred source of control for the bionic hands. This is because patients can contract the muscles at will and the electrical activity generated by the contractions can be used to tell the prosthetic hand what to do, for example open or close. A major problem at higher amputation levels, such as above the elbow, is that there aren’t many muscles left to control the many robotic joints needed to truly restore function to an arm and hand.

A multidisciplinary team of surgeons and engineers has overcome this obstacle by reconfiguring the stump and integrating sensors and a bone implant to connect it with a prosthesis, electrically and mechanically. By intervening in peripheral nerves and redistributing them to new muscle targets used as biological amplifiers, the bionic prosthesis can now access much more information so that the user can control the movements of the robotic prosthesis much more precisely.

The team includes, among others, Jan Zbinden, from the Center for Bionics and Pain Research (CBPR) in Sweden, as well as Max Ortiz Catalan, founding director of CBPR, head of neural prosthetics research at the Australian Institute of Bionics, and professor of bionics at Chalmers University of Technology in Sweden.

Patient with a prosthesis in the laboratory of the Center for Bionics and Pain Research. (Photo: Chalmers University of technology / Anna-Lena Lundqvist. CC BY ND)

The team has shown that “rewiring” the nerves so that they provide their service at the most suitable points of the musculature is not only possible, but also improves prosthetic control.

Zbinden, Catalan, and their colleagues report the technical details of their breakthrough in the academic journal Science Translational Medicine, under the title “Improved control of a prosthetic limb by surgically creating electro-neuromuscular constructs with implanted electrodes.” (Fountain: NCYT by Amazings)