A female patient in Sweden with an amputated hand has become the world's first recipient of an osseo-neuromuscular implant that controls a dextrous hand prosthesis. The pioneering surgery involved placing titanium implants in the radius and ulnar (forearm bones). From these implants, electrodes to nerves and muscle were extended which extract signals to control a robot hand and provide a tactile sensation.
The successful surgery has now become the first clinically viable, sentient and dextrous prosthetic hand useable in real life.
The implant technology was developed in Sweden at Integrum AB, by a team led by Dr Max Ortiz Catalan, and Chalmers University of Technology. In a few weeks, it is expected that the patient will be using a prosthetic hand with increased sensations and functionality in everyday life. Two more patients will receive the implants for this new generation of prosthetic hand in the coming months, in Sweden and in Italy.
New osseo-neuromuscular implant
A patient tests the new hand technology and will be fitted with the hand in the coming weeks. photo credit: Dr Max Catalan
Current prosthetic hands only allow control of certain gross movements, such as opening and closing the hand. They rely on electrodes over the skin that extract control signals from the muscles underlying the stump. More reliable and richer information can be obtained by the implant of electrodes in remaining stump muscles. In this first patient, sixteen electrodes were planted allowing for the achievement of more dextrous control of a prosthetic hand.
Conventional prosthetic hands also have a limited sensory feedback. Users are unable to gauge the strength that an object is being grasped, or even the moment that contact has been made. When electrodes are implanted in the nerves that used to be connected to the lost biological sensors in the hand, the nerves can be electrically stimulated in a way similar to that of a biological hand. The result is that patients perceive sensations in the prosthetic hand as it is also equipped with nerve stimulation sensors.
One of the most important elements of this work is that it is the first such technology that is also usable in every life. Everyday usability was previously only possible in above-elbow amputees.
Unlike older technologies, the new osseo-neuromuscular implants require no socket over the stump. The sockets could be cumbersome, limit mobility and cause discomfort or pain to the user. Instead, the new technology relays on integrated bone tissue and titanium, which anchors the prosthesis directly onto the skeleton via a process known as osseointegration.
“Several advanced prosthetic technologies have been reported in the last decade, but unfortunately they have remained as research concepts used only for short periods of time in controlled environments,” says Dr. Ortiz Catalan, who has been leading development since its beginning a decade ago. “The breakthrough of our technology consists of enabling patients to use implanted neuromuscular interfaces to control their prosthesis while perceiving sensations where it matters for them, in their daily life.”
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