2023-07-14 12:42:56
by Ruggiero Corcella
An international study published in Science Translational Medicine demonstrates how the grafting of a bionic implant to the residual limb works
We entered full cyborg era? By now, creating cybernetic or bionic organisms is no longer the prerogative of some visionary science fiction authors such as William Gibson, the inventor of the word “cyberspace”. In his “Neuromancer” (Sprawl Trilogy) the integration between human bodies and artificial – or even digital – bodies is normal.
We have not yet reached this level of perfection, but experiments like the one just completed in Sweden by the Chalmers University of Technology in Gothenburg together with other international partners (including the Rizzoli Orthopedic Institute in Bologna and the Scuola Superiore Sant’Anna of Pisa) are already paving the way. Thanks to the grafting of a bionic implant to the residual limb, an amputee patient has shown that he can use each finger of a bionic hand as if it were his own. The study was published in Science Translational Medicine.
What is the new intervention?
The experimentation is the result of a collaboration that involved various specialties: from robotics to orthopedic surgery and is an evolution compared to previous attempts also carried out in Gothenburg in 2017 and 2019. So what’s new? «Until now there has been a big evolution on the robotic component, i.e. the hardware, the way of transmitting messages to the artificial limb remained quite rudimentary – explains Professor Marco Innocenti, director of the Clinical Complex Structure IV – Orthoplasty. Rizzoli Orthopedic Institute of Bologna -. Then external sensors were placed on certain muscles of the residual limb and the patient learned to contract certain muscles to have a certain functional effect».
«With this new technology devised in Gothenburg, the bionic limb is connected to the stump of the residual limb via a titanium or steel stem that comes out of the medullary canal of the bone. Electrodes connected to electrical wires inside the arm are implanted on this stem. The surgeon operates on the stump of the nerve, divides it into various branches, tries to identify the function of these branches and attaches an electrode to it. The electrode then communicates with the robotic stem. The big difference is that with this type of device the patient thinks he is flexing his index finger and flexes his index finger because it sends a physiological stimulus to a nerve», adds Professor Innocenti, already full professor of Plastic, Reconstructive and Aesthetic Surgery at the University of Florence and extraordinary in Plastic, Reconstructive and Aesthetic Surgery at the University of Bologna.
Obstacles and solutions
Prostheses are the most common solution to replace a lost extremity. However, they are difficult to control and often unreliable with only a couple of motions available. The “surviving” muscles in the residual limb are the preferred source of control for the bionic hands. This is because patients can contract their muscles at will, and the electrical activity generated by the contractions can be used to tell the prosthetic hand what to do, such as open or close. A major problem at higher-positioned amputation levels, such as above the elbow, is that not many muscles remain to command the many robotic joints needed to truly restore function to an arm and hand.
The multidisciplinary team of surgeons and engineers coordinated by Chalmers University of Technology in Gothenburg got around this problem by reconfiguring the residual limb and integrating sensors and a skeletal implant to connect electrically and mechanically to a prosthesis. By dissecting 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 command many robotic joints at will.
Rewiring of the nerves which promotes better prosthetic control
The research was led by Professor Max Ortiz Catalan, founding director of the Center for Bionics and Pain Research (CBPR) in Sweden, head of neural prosthesis research at the Bionics Institute in Australia and professor of bionics at Chalmers University of Technology in Sweden . “We demonstrate that rewiring nerves to different muscle targets in a distributed and simultaneous manner is not only possible, but also promotes better prosthetic control. A key feature of our work is that we have the ability to clinically implement more refined surgeries and embed sensors into neuromuscular constructs at the time of surgery, which we then connect to the prosthesis electronics via an osseointegrated interface. Artificial Intelligence algorithms take care of the rest,” say the researchers.
High level of functionality
Prosthetic limbs are commonly attached to the body by a grip that compresses the residual limb causing discomfort and is mechanically unstable. An alternative to socket attachment is to use a titanium implant placed within the residual bone which becomes strongly anchored: this is known as osseointegration. This skeletal attachment allows for a more efficient and comfortable mechanical connection of the prosthesis to the body.
“It is gratifying to see that our cutting-edge engineering and surgical innovation can provide such a high level of function for an individual with an arm amputation. This achievement builds on more than 30 years of step-by-step concept development, in which I am proud to have contributed,” comments Dr. Rickard Brånemark, Research Affiliate at MIT, Associate Professor at the University of Gothenburg, CEO of Integrum, one of the leading experts in osseointegration for limb prosthetics, who conducted the interface implantation.
One-finger control and sensory feedback
The surgery took place at the Sahlgrenska University Hospital, Sweden, headquarters of the CBPR. The neuromuscular reconstruction procedure was conducted by Dr. Paolo Sassu, who also led the first hand transplant performed in Scandinavia. “The incredible journey we have embarked on together with the bionic engineers at CBPR has allowed us to combine novel microsurgical techniques with sophisticated implanted electrodes that provide single-finger control of a prosthetic arm and sensory feedback. Patients who have had an arm amputation could now see a brighter future,” says Dr. Sassu, who currently works at the Rizzoli Orthopedic Institute in Italy.
The study illustrates how nerves progressively connect to their new host muscles. Once the innervation process was advanced enough, the researchers connected them to the prosthesis so that the patient could control each finger on a prosthetic hand as if it were her own. The researchers also demonstrated how the system responds in activities of daily living and are currently in the process of further improving the controllability of the bionic hand.
July 14, 2023 (change July 14, 2023 | 12:38)
© Time.News
#control #artificial #fingers #real #time.news