For 24 years, Sam Rosecrans relied on his right arm to do his bidding. When he cast his fishing line, ate dinner with his family, or headed out to work, his arm was there, effortlessly completing every task. Billions of neurons were sending electrical messages between his brain and nervous system, dictating the fluid motion of his shoulder, elbow, wrist, and fingers, a natural biomechanical process that functioned unnoticeably until July 1, 2015.
