Experimental tests on robotic prosthesis:
clothespin. Credit: 2024 Scuola Superiore Sant'Anna
It is the
first magnetically controlled prosthetic hand that allows amputees to reproduce
all movements simply by thinking and to control the force applied when grasping
fragile objects. No wires, no electrical connection, only magnets and muscles
to control the movements of the fingers and enable everyday activities such as
opening a jar, using a screwdriver, picking up a coin.
A research team from the BioRobotics Institute of the
Scuola Superiore Sant'Anna in Pisa, coordinated by Prof. Christian Cipriani,
has developed a radically new interface between the residual arm of the amputee
and the robotic hand to decode motor intentions.
The system involves implanting small magnets into the
muscles of the forearm. The implant, integrated with the Mia-Hand robotic hand
developed by the spin-off Prensilia, was successfully tested on the first
patient, a 34-year-old Italian named Daniel, who used the prosthesis for six
weeks.
The results of the trial were presented in the journal Science
Robotics and represent a significant step forward for the future of
prostheses.
"This result rewards a decades-long research path. We have finally developed a functional prosthesis that meets the needs of a person who has lost a hand," says Christian Cipriani, professor at the BioRobotics Institute of the Scuola Superiore Sant'Anna.
Documentary on the study published in Science
Robotics. Interview with Christian Cipriani, scientific head of the
project, Dr. Lorenzo Andreani, Orthopaedics and Traumatology 2 Operative Unit,
and the patient. Credit: 2024 Scuola Superiore Sant'Anna
Myokinetic control for the development of a natural
prosthesis
Myokinetic control is the decoding of motor intentions by means of
implantable magnets in the muscles. This is the frontier explored by the
research team of the Scuola Superiore Sant'Anna to revolutionize the future of
prostheses.
The idea behind the new interface, developed as part of the MYKI project, is to use small magnets, a few millimeters in size, to be implanted in the residual muscles of the amputated arm and use the movement resulting from contraction to open and close the fingers.
Experimental tests on robotic prosthesis: grip on
bottle. Credit: 2024 Scuola Superiore Sant'Anna
"There are 20 muscles in the forearm and many of them control the hand
movements. Many people who have lost a hand keep on feeling it as if it is
still in place and the residual muscles move in response to the commands from
the brain," Cipriani explains.
The research team mapped the movements and translated them into signals to
guide the fingers of the robotic hand. The magnets have a natural magnetic
field that can be easily localized in space. When the muscle contracts, the
magnet moves and a special algorithm translates this change into a specific
command for the robotic hand.
The first patient to test the new prosthesis
Daniel lost his left hand in September 2022: "I suddenly found myself without a hand: one moment I had it and the next moment it was gone." He was selected as a volunteer for the study because he still felt the presence of his hand and the residual muscles in his arm responded to his movement intentions.
Experimental tests on robotic prosthesis: handshake.
Credit: 2024 Scuola Superiore Sant'Anna
In April 2023,
Daniel underwent surgery to implant magnets in his arm. The surgery was carried
out at the Azienda Ospedaliero-Universitaria Pisana (AOUP), thanks to the
collaboration of a team coordinated by Dr. Lorenzo Andreani of the Orthopedics
and Traumatology 2 Operative Unit, Dr. Manuela Nicastro of the Anesthesia and
Reanimation Orthopedics and Burns Center unit, and Dr. Carmelo Chisari of the
Neurorehabilitation unit.
"This is a significant advancement in the field
of advanced prosthetic medicine," says Dr. Lorenzo Andreani.
"The surgery was successful thanks to a careful
patient selection process based on strict criteria. One of the most complex
challenges was identifying the residual muscles in the amputation area, which
were precisely selected using preoperative MRI imaging and electromyography.
However, the actual condition of the tissue, due to scarring and fibrosis,
required intraoperative adaptation.
"Despite these difficulties, we were able to
complete the implant and establish the connections—a success that would have
been impossible without the collaboration of an exceptional team, whom I would
like to thank.
"Starting with Dr. Manuela Nicastro, head of anesthesia, to the nurses who worked with dedication and professionalism, contributing decisively to the positive outcome of the operation, which represents an important step forward in medical research."
Experimental tests on robotic prosthesis: patient
pours water into a glass. Credit: 2024 Scuola Superiore Sant'Anna
Six magnets
were implanted in Daniel's arm. For each one, the team of surgeons and doctors
located and isolated the muscle, positioned the magnet and checked that the magnetic field was oriented
in the same way.
"To make the connection between the residual arm
where the magnets were implanted and the robotic hand easier, we made a carbon fiber prosthetic socket containing the electronic system capable of
localizing the movement of the magnets," Cipriani explains.
The results of the experiment went far beyond the most optimistic expectations. Daniel was able to control the movements of his fingers, pick up and move objects of different shapes, perform classic everyday actions such as opening a jar, using a screwdriver, cutting with a knife, closing a zip; he was also able to control the force when he had to grasp fragile objects.
Experimental tests on robotic prosthesis: patient opens a jar. Credit: 2024 Scuola Superiore Sant'Anna
Experimental tests on robotic prosthesis: patient grasps a plastic cup. Credit: 2024 Scuola Superiore
"This system allowed me to recover lost sensations and emotions: it feels like I'm moving my own hand," says Daniel.
"To see the work of years of research realized in
this study was a great emotion. Working together with Daniel has given us the
awareness that we can do a lot to improve his life and the lives of many other
people. This is the greatest motivation that drives us to continue our work and
to always do better," explains Marta Gherardini, assistant professor at
the Scuola Superiore Sant'Anna and first author of the study.
"We are ready to extend these results to a broader range of amputations," Cipriani concludes. "In fact, our work on this new implant is going ahead thanks to European and national funding."
by Sant'Anna School of Advanced Studies, Pisa
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