Video: Swede fitted with first mind-controlled prosthetic arm

Posted Oct 13, 2014 by JohnThomas Didymus
A 42-year-old Swede who lost his right arm over 10 years ago has become the world's first arm amputee to be fitted with a mind-controlled prosthetic arm directly connected to his bone, nerves and muscles.
His mind-controlled artificial arm, almost as good as the real thing, has allowed him to keep his job as a truck driver, which involves a variety of physically demanding activities, such as operating machinery and securing trailer loads. He is also able to perform delicate and complicated tasks, such as handling eggs and helping his children tie their skate laces.
The remarkable performance of the artificial limb was the subject of a report titled, "An osseointegrated human-machine gateway for long-term sensory feedback and motor control of artificial limbs," published Oct. 8, 2014 in the journal Science Translational Medicine.
The patient, identified simply as Magnus, probably the world's first cyborg, was originally fitted with a prosthesis controlled through electrode sockets attached to his skin. But in January 2013, he was fitted with an osseointegrated or bone-anchored prosthetic arm designed by researchers at Chalmers University of Technology in Gothenburg, led by Max Ortiz Catalan and Professor Bo Håkansson.
Osseointergration means that the artificial arm is attached directly to the humerus bone at the base of his upper arm, instead of being attached to his skin using sockets. Implanted neuromuscular electrode interfaces connect his nerves and muscles to the machine's control system. The electrodes are able to read and interpret electrical motor signals from the brain, allowing him to use his mind to control the artificial arm.
Traditional prosthetic limbs secured using non-invasive electrodes attached to the surface of the patient's skin suffer the disadvantage of electrical activity interference. The "cross-talk" limits the ability of the control system to read motor signals from relevant arm muscles and manage sensory feedback from the artificial arm. Besides the "cross-talk," the pressure of the sockets on the skin also caused patients pain and tissue damage, forcing many to abandon their prosthetic limbs.
But osseointegration technology not only allows for improved performance — it also helps to overcome the physical inconveniences of the old-style prostheses.
A YouTube video (see above) shows Magnus performing a variety of tasks with his mind-controlled artificial limb. He is able to hold an egg without cracking the shell. He is able to use a drill, fetch a glass from a cupboard and handle a handkerchief deftly. The video contrasts the functionality of the new bone-anchored prosthesis with the old-style skin-anchored prosthesis.
The technique of osseointegration was pioneered by associate professor Rickard Brånemark and colleagues at the Sahlgrenska University Hospital in Sweden. Brånemark and his team helped their colleagues at Chalmers to surgically implant the prosthesis.
Max Ortiz Catalan, who led the study at the Chalmers University, said, "We have used osseointegration to create a long-term stable fusion between man and machine. The artificial arm is directly attached to the skeleton, thus providing mechanical stability. Then the human's biological control system is also interfaced to the machine's control system via neuromuscular electrodes. This creates an intimate union between the body and the machine; between biology and mechatronics."
Magnus is the first patient to use the new prosthetic limb outside the experimental laboratory. According to Catalan, "Going beyond the lab to allow the patient to face real-world challenges is the main contribution of this work."
The researchers are working on further improvements to the device. The main thrust of the effort is to develop a prosthesis that allows the user to experience sensations. The prosthesis has a bidirectional interface design which means it is designed to receive and send signals to the brain. Presently, Magnus is able to use his mind to control the artificial limb through signals sent from his brain. To also experience artificial sensations, the interface would have to be able to transmit signals which the brain can interpret as sensations.
Although the interface already has a bidirectional design, the researchers have not fully developed and implemented its sensory feedback capability. The researchers hope that Magnus will soon be able to enjoy the advantages of this special function and that other patients will be able to benefit from the new technology.
"Reliable communication between the prosthesis and the body has been the missing link for the clinical implementation of neural control and sensory feedback, and this is now in place. So far we have shown that the patient has a long-term stable ability to perceive touch in different locations in the missing hand... this has only been possible in short experiments within controlled environments," Catalan said.
Researchers at Case Western Reserve University (CWRU) and the Cleveland Veterans Affairs Medical Center are also working independently on developing artificial sensation in amputees fitted with prostheses.
Igor Spetic, one of the patients participating in the project, who lost his right hand in an accident four years ago, was able to experience sensations through electrical stimulation of his brain using signals sent from an artificial interface.
Spetic reported being able to distinguish 19 different textures.
The benefits of restoration of sensation for amputees include relief of the "phantom pain" many feel after amputation, and increased ability to handle and manipulate delicate objects.