For the first time an operation has been conducted, at Sahlgrenska University Hospital, where electrodes have been permanently implanted in nerves and muscles of an amputee to directly control an arm prosthesis. The result allows natural control of an advanced robotic prosthesis, similarly to the motions of a natural limb.
A surgical team led by Dr Rickard Brånemark, Sahlgrenska University Hospital, has carried out the first operation of its kind, where neuromuscular electrodes have been permanently implanted in an amputee. The operation was possible thanks to new advanced technology developed by Max Ortiz Catalan, supervised by Rickard Brånemark at Sahlgrenska University Hospital and Bo Håkansson at Chalmers University of Technology.
"The new technology is a major breakthrough that has many advantages over current technology, which provides very limited functionality to patients with missing limbs," says Rickard Brånemark.
Big challenges
There have been two major issues on the advancement of robotic prostheses: 1) how to firmly attach an artificial limb to the human body; 2) how to intuitively and efficiently control the prosthesis in order to be truly useful and regain lost functionality.
"This technology solves both these problems by combining a bone anchored prosthesis with implanted electrodes," said Rickard Brånemark, who along with his team has developed a pioneering implant system called Opra, Osseointegrated Prostheses for the Rehabilitation of Amputees.
A titanium screw, so-called osseointegrated implant, is used to anchor the prosthesis directly to the stump, which provides many advantages over a traditionally used socket prosthesis.
"It allows complete degree of motion for the patient, fewer skin related problems and a more natural feeling that the prosthesis is part of the body. Overall, it brings better quality of life to people who are amputees," says Rickard Brånemark.
How it works
Presently, robotic prostheses rely on electrodes over the skin to pick up the muscles electrical activity to drive few actions by the prosthesis. The problem with this approach is that normally only two functions are regained out of the tens of different movements an able-body is capable of. By using implanted electrodes, more signals can be retrieved, and therefore control of more movements is possible. Furthermore, it is also possible to provide the patient with natural perception, or "feeling", through neural stimulation.