A research team from the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md, has developed a prototype of the first fully integrated prosthetic arm. According to the APL-led Revolutionizing Prosthetics 2009 (RP 2009) team, the prosthetic arm can be controlled naturally, can provide sensory feedback, and allow eight degrees of freedom.

“This progress represents the first major step in a very challenging program that spans 4 years and involves more than 30 partners, including government agencies, universities, and private firms from the United States, Europe, and Canada,” says Stuart Harshbarger, PhD, who lead the program. “The development of this first prototype within the first year of this program is a remarkable accomplishment by a talented and motivated team and serves as validation that we will be able to implement Defense Advanced Research Projects Agency’s (DARPA) vision to provide, by 2009, a mechanical arm that closely mimics the properties and sensory perception of a biological limb.”

Proto 1, developed for the DARPA Revolutionizing Prosthetics Program, is a complete limb system that includes a virtual environment used for patient training, clinical configuration, and to record limb movements and control signals during clinical investigations.

The natural control and integrated sensory feedback demonstrated with Proto 1 is enabled by Targeted Muscle Reinnervation, a technique pioneered by Todd Kuiken, MD, PhD, at the Rehabilitation Institute of Chicago (RIC). It involves the transfer of residual nerves from an amputated limb to unused muscle regions in appropriate proximity to the injury.

During the clinical evaluation of the limb at RIC, Jesse Sullivan, a patient of Kuiken, demonstrated the ability to reposition his thumb for different grips, remove a credit card from a pocket, stack cups while controlling his grip force using sensory feedback verses vision, and to walk using the free swing mode of the limb for a more natural gait.

Researchers at APL, who were responsible for much of the design and fabrication of Proto 1, and other team members, are already working on a second prototype, which is expected to be unveiled this summer.