Nothing replaces the parts you were born with, but technology is making artificial limbs steadily better — and just in time. Partly because of the growing number of veterans returning from the Iraq war, the population of amputees living in the U.S. will increase 42% by 2020. Scientists at Johns Hopkins University have developed a revolutionary prototype for a prosthetic arm that lets the user grip objects by connecting remaining nerves near the injury with unused muscles that can then flex and operate the hand. Meanwhile, Hanger Orthopedic Group in Bethesda, Md., has developed a suction-producing gel that helps comfortably hold the fake limb in place, enhancing the traditional stump-and-socket attachment, which can cause painful skin infections.