A bilateral shoulder-level amputee made history at the Johns Hopkins University Applied Physics Laboratory, Baltimore, MD, this summer when he became the first person to wear and simultaneously control two of the Laboratory’s Modular Prosthetic Limbs. He was able to operate the system by simply thinking about moving his limbs, performing a variety of tasks during a short training period.
He underwent a surgical procedure to reassign nerves that once controlled the arm and the hand, called reinnervation. A custom socket for his torso and shoulders was made to support the prosthetic limbs and makes neurological connections with his reinnervated nerves.
Using pattern recognition algorithms to identify individual muscles that are contracting, how well they communicate with each other, and their amplitude and frequency, the researchers translated that data into actual movements within a prosthetic.
The research team then had the amputee work with the limb system through a virtual-reality system that’s being used to test novel neural interface methods and study phantom limb pain, as well as serve as a portable training system.
When fitted with the custom socket, and the prosthetic limbs were attached, the amputee was able to move several objects, including an empty cup from a counter-shelf height to a higher shelf, a task that required him to coordinate the control of eight separate motions to complete.
The team was surprised by the speed with which he learned motions and the number of motions he was able to control in such a short period of time, as well as his ability to control a combination of motions across both arms at the same time. This, they said, was a first for simultaneous bimanual control.