A bionic arm with eight motors that restores heat and pressure sensations, a hand with five independently-moving fingers that automatically senses and adjusts for resistance ? the world of replacement limbs is getting more complex at a dizzying pace this summer.

Scotland-based Touch Bionics this week announced it produced a fully articulated bionic hand that can receive a handshake, grip a tennis ball or turn a doorknob without intense concentration by the patient.