"The main advantage of this system, and what makes it a world first, is that all components are directly implanted at the amputation site with a closed control circuit. Information runs into the prostheses and from there back into the brain," explains Aszmann. "Signal transmission from the prosthesis into the stump and via specific nerve interfaces onwards to the person's brain is so detailed that the patient is able to perceive individual fingers of the prosthesis in real time, for example."
Here, sensors which are incorporated in a prosthesis from MedUni Vienna's commercial partner Otto Bock Healthcare Products are directly coupled to the appropriate neural pathways to create a user-friendly "Plug and Play" system, says Aszmann. In previous bionic reconstructions, some patients needed weeks or months of training before they could use a prosthesis properly.
This implant, for the first time, allows for bidirectional communication between a prosthetic hand and electrodes implanted in the nerves and muscles of the upper arm and was anchored to the humerus through osseointegration.
Connecting nerves directly to the prosthesis
A surgical procedure lasting 6 – 8-hours is required. During this procedure, a titanium implant is placed in the bones on the upper arm and the nerves are wired with a novel system developed together with MIT Harvard and Integrum at Chalmers University in such a way that signals arrive directly in the prosthesis, as it were, and are conducted back again from there. For the first time, this system is self-contained and everything takes place directly in the arm. The battery inserts directly into the prosthesis and can easily be removed in the evening for recharging. Says Aszmann: "We have developed this system over the last four years and we are also extremely satisfied with the long-term stability of signal transmission."
So far, it has been used in four male patients who have had upper-arm amputations.
Bionic limb reconstruction: MedUni Vienna a global leader
In July 2019, shortly after opening of the Clinical Laboratory for Bionic Limb Reconstruction at MedUni Vienna's Department of Surgery, the research group, working together with the Alfred Mann Foundation from the USA, successfully managed, for the first time in the world, to implant sensors in three male patients following nerve transfers, to transmit biosignals for wireless control of bionic prostheses.
"Our new findings in the recent study and our collaboration with MIT in Massachusetts, one of the greatest technical universities in the world with more than 10,000 students, underscores the position that the Medical University of Vienna has established for itself as a world leader in the field of bionic limb reconstruction," stresses Aszmann.
Service: New England Journal of Medicine
"Self-contained Neuromusculoskeletal Arm Prostheses.” Max Ortiz‑Catalan, Enzo Mastinu, Paolo Sassu, Oskar Aszmann and Rickard Branemark. N Engl J Med 2020;382:1732-8.