Karen Sussex of Jackson, Mich., folds and hangs laundry using her body-powered prosthesis — a limited, decades-old technology that many amputees still prefer due to its simplicity and reliability. Sussex is a participant in an advanced prosthetics study at the University of Michigan.

Abstract

Losing a limb can be a devastating setback that science and technology struggle to fully offset, even after thousands of years of effort. Prosthetic devices in use today offer limited functionality or can be too cumbersome for amputees to use effectively.

While advanced robotic hands exist, amputees don’t have ways to intuitively control them. That lack of naturalistic control contributes, in many cases, to some abandoning their prostheses because they find life easier without them. [1]

A biological interface developed by clinicians and engineers at the University of Michigan is giving amputees new, intuitive control of the most advanced robotic hands on the market. Their new approach centers on the Regenerative Peripheral Nerve Interface (RPNI)—a small graft of muscle tissue surgically attached to the end of a severed nerve in an amputee’s arm.

While other neural interfaces are harmful to nerves, the RPNI promotes healthy nerve growth and acts as a bioamplifier, converting faint neural signals sent from the brain into large, recordable, muscle signals that remain stable for years. Combined with machine learning algorithms, these signals enable intuitive, real-time mind control of advanced robotic prosthetic hands.

The RPNI grafts also impede the growth of painful neuromas at the severed ends of nerves, reducing: the need for chronic pain medication, repeated surgical procedures, and an inability to use prosthetics due to pain levels.