MedUni Vienna: Breakthrough in bionic prostheses: Restoration of feeling possible with artificial limbs

Despite enormous progress over the past two decades, patients have not yet been able to feel a bionic prosthesis in a natural, intuitive way. Now a research team led by Oskar Aszmann from MedUni Vienna has made significant progress in sensitising the artificial extremities: By developing a new type of interface between man and machine, the feeling of the lost limb has been restored for the first time. The results of the study, which were recently published in the renowned journal "Nature Communications", can make it possible to perceive the prosthesis as one's own body part.

The fact that patients are unable to perceive their bionic prosthesis as their own limb is primarily due to the inadequacies of the human-machine interface. In the search for ways to improve prosthetic control and a more natural body sensation, the scientists led by Oskar Aszmann (Department of Plastic, Reconstructive and Aesthetic Surgery, Clinical Laboratory for Bionic Limb Reconstruction, MedUni Vienna) carried out the most detailed investigation of a biological interface between patient and prosthesis to date. A nerve, which contains both sensory and motor fibres, was connected to a non-associated muscle, to which a skin graft was also grafted. "The nerve then grew into the muscle and skin and formed new, functional connections with the muscle fibres as well as mechanoreceptors that perceive movement and touch - a process we call reinnervation," reports principal investigator Oskar Aszmann on the research, which represents a breakthrough in bionic reconstruction.

Redirection of severed nerve

As the investigations on the animal model have shown, a severed nerve, such as after the amputation of an extremity, can be rerouted to previously unrelated muscles and skin, thereby restoring the flow of information. "In this way, we have created a neuromuscular landscape in the amputation stump that maps the lost limb," says Oskar Aszmann. This newly developed human-machine interface showed the researchers an extraordinarily dense nerve fibre network in the transplanted skin, which restored connections to the natural touch sensors of the lost hand. In addition, the sensory organs of the muscles (muscle spindles) and Golgi tendon organs located in the musculotendinous passage proved to be so robustly reinnervated that they can restore the sense of embodiment to a previously unreached degree. "This is the first time we have been able to show that a nerve that has lost its target after an amputation can re-innervate an artificially created sensorimotor construct," emphasises Oskar Aszmann. In plain language, the results of the study make it possible for patients to feel and move their artificial limb as if it belonged to their own body. The next step will be to confirm the findings from the animal model in studies on patients with bionic prostheses. Aszmann: "I am convinced that the method will also work in humans."

Publication: Nature Communications

Creation of a biological sensorimotor interface for bionic reconstruction;   
Christopher Festin, Joachim Ortmayr, Udo Maierhofer, Vlad Tereshenko, Roland Blumer, Martin Schmoll, Génova Carrero-Rojas, Matthias Luft, Gregor Laengle, Dario Farina, Konstantin D. Bergmeister & Oskar C. Aszmann;
DOI: 10.1038/s41467-024-49580-8
https://www.nature.com/articles/s41467-024-49580-8

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