Science, as well as science fiction, has long dreamed of replacing lost or damaged (or simply inadequate) human limbs with bionic prosthetics. Progress has been slow to date, as it’s notoriously hard to get the human body to accept non-biological materials as ‘part of the furniture’. A breakthrough at University College, London may change all that though – a way of securing a titanium rod into human bone, and having the skin heal and mesh around it without bleeding or infections.