A Swedish woman whose hand was amputated has become the first recipient of an osseo-neuromuscular implant to control a dexterous hand prosthesis, according to Chalmers University of Technology in Gothenburg, Sweden.

Surgeons placed titanium implants in the two forearm bones (radius and ulna), and extended electrodes to nerves and muscle to extract signals to control a robotic hand and provide tactile sensations. Chalmers University and the European Dextrous Transradial Osseointegrated Project (DeTOP) declared it the first clinically viable, dexterous and sentient prosthetic hand usable in real life.

Conventional prosthetic hands rely on electrodes placed over the skin to extract control signals from the underlying stump muscles. These superficial electrodes deliver limited and unreliable signals that only allow control of a couple of gross movements, such as opening and closing the hand.

Richer and more reliable information can be obtained by implanting electrodes in all remaining muscle in the stump instead, according to a statement from Chalmers University. Sixteen electrodes were implanted in this first patient in order to achieve more dexterous control of a novel prosthetic hand developed in Italy by the Scuola Superiore Sant’Anna and Prensilia.

Current prosthetic hands have also limited sensory feedback, making it difficult for users to tell how strongly an object is grasped or even when contact has been made. By having electrodes implanted in the nerves that used to be connected to the biological sensors of the hand, the patient can perceive sensations originating in the prosthetic hand.

The implant technology was developed in Sweden by a team lead by Max Ortiz Catalan at Integrum AB — the company behind the first bone-anchored limb prosthesis using osseointegration — and Chalmers University.

This first-of-its-kind surgery, led by Rickard Brånemark, M.D., and Paolo Sassu, M.D, took place at Sahlgrenska University Hospital as part of a larger project funded by the European Commission under DeTOP. Integrum and Chalmers University previously demonstrated that control of a sentient prosthesis in daily life was possible in above-elbow amputees using similar technology.

The patient with the new implant is learning how to control it using virtual reality. In a few weeks, she will begin using a prosthetic hand with increasing function and sensations. Two more patients will be implanted with this new generation of prosthetic hands in the coming months, in Italy and Sweden.

“Several advanced prosthetic technologies have been reported in the last decade, but unfortunately, they have remained as research concepts used only for short periods of time in controlled environments,” said Ortiz Catalan, who also heads the Biomechatronics and Neurorehabilitation Lab at Chalmers University. “The breakthrough of our technology consists of enabling patients to use implanted neuromuscular interfaces to control their prosthesis while perceiving sensations where it matters for them, in their daily life.”

About the author:

Nancy Crotti is a frequent contributor to WTWH Media publications.