Research in the field of wireless biosignal transmission is no longer a fringe phenomenon in the field of modern prosthetics. A large number of international research groups are working on potential solutions to create a more fluent man-machine interface. For the first time in the world, the research group led by Oskar Aszmann from MedUni Vienna’s Department of Surgery, working with partners from Otto Bock Healthcare Products, Alfred Mann Foundation, and Imperial College London, has successfully implanted sensors in three male patients following nerve transfers, to transmit biosignals for wireless control of robotic arms. “After more than two years of observation, the results demonstrate extremely reliable data transmission and much quicker and safer use in comparison with standard systems,” says Principal Investigator Aszmann, who is very happy with this pilot project.

The international research group is confident that, in the near future, wireless biosignal transmission systems will not only be used in the area of modern prosthetics but also make an important contribution in many other biotechnology sectors. “These patients had had above-elbow amputations as a result of occupational or road accidents. In such cases, they not only have to have the hand and the wrist replaced by a myoelectric prosthesis but the elbow as well. The implanted sensors transmit the muscle signal wirelessly from the amputation stump to the prosthesis and are similarly wirelessly charged by a magnetic coil in the shaft of the prosthesis,” explains study author Stefan Salminger from MedUni Vienna’s Department of Surgery.

In combination with selective extension of the nerves that were responsible for hand and arm function before the amputation, these patients are able to control the prosthesis intuitively. This implantable technology could make a significant improvement in muscle signal quality, in particular, and, above all in the reliability of prosthesis control.

An overview of the new system. (c) Imperial College London

Co-author Professor Dario Farina, of Imperial’s Department of Bioengineering, said: “Although this was demonstrated in only three people, the results are promising. From here, we hope to test the technique on more amputees to refine our method and make sure it’s fit to be used in more people with amputations.”

All participants of the study reported that they preferred the new system and wanted to keep it after the end of the experimental period – and that it worked both in clinic and at home.

Professor Farina said: “Current prosthetics have come a long way since their inception. However, there’s still a lot of room for improvement. We wanted to address the issues that cause frustration and even embarrassment to users, and ultimately improve amputees’ quality of life.”

The researchers recruited three men aged 16, 31, and 47 with above-elbow arm amputation – a particularly challenging type of amputation.

Following surgery to relocate nerves to the stump and implant the electrodes, they fitted the prostheses and followed the patients’ progress and their prosthetics’ performance for more than two years. This makes this the first long-term study to combine implantable systems with nerve transfer surgery.

In addition, the scientists plan to further improve the man-machine interface by giving prosthetics the power of sensing their environment.

Professor Farina said: “We know that in healthy individuals, feedback from the prosthetic is very important for amputees to perceive the limb as a part of their own body. “We hope our work here and in the future will go some way to make this happen.”

Source: Medical University of Vienna and Imperial College London