Surgeons used a new technique to attach a thought-controlled robot arm directly to an amputee’s stump, giving him a far greater range of motion with the advanced prosthetic limb.
The system, involving an implant inserted into the bone at the end of the residual limb, allows test patient Johnny Matheny to use the arm without the constraining and sometimes uncomfortable harness he previously used when experimenting with the Modular Prosthetic Limb (MPL).
“It’s all natural now,” Metheny says after his first trial run using the MPL with the new implant. “Nothing is holding me down. Before, I had limited range; I couldn’t reach over my head and behind my back. Now—boom!—that limitation is gone.”
Matheny, whose left arm was amputated in 2008 because of cancer, is a pioneer of advanced arm prosthetics. He was the first patient at the Johns Hopkins Hospital to undergo targeted muscle reinnervation, surgery that reassigns the nerves that once controlled the arm or hand.
That surgery is what makes it possible for him to use and control an advanced prosthetic device like the MPL much as a non-amputee would use an arm: the brain send signals through the nerves to direct movement.
The combination in Matheny of both the reinnervation and the implanted connection system is another first for the Revolutionizing Prosthetics program, a Defense Department-funded effort led by the Applied Physics Laboratory. The goal is to provide better functionality for soldiers and for civilian amputees as well.