A spine model implanted with a titanium tube is displayed at Peking University Third Hospital in Beijing, August 14, 2014. Chinese doctor Liu Zhongjun has successfully implanted an artificial axis produced by a 3D printer into the spine of a bone cancer patient. This was the first time that an axis produced by 3D printing had been implanted into a patient, according to Liu. Normally, a diseased axis would be replaced by a standardised, hollow titanium tube, said Liu. Picture taken August 14, 2014. REUTERS/Jason Lee (CHINA - Tags: SCIENCE TECHNOLOGY HEALTH)