Zhang Jingui, 84, had his knee joint repaired Nov 21 using the world's first customized 3D-printed tantalum metal pad at Southwest Hospital affiliated with the Army Medical University in Southwest China's Chongqing.

On the first day after the operation, the patient could get off the bed and walk with assistance. In a week, he could leave the hospital to receive recovery treatment and training.

At present, titanium alloy is mainly used in this field. Tantalum is more suitable than other metals for use in the human body, but ordinary 3D printers cannot use tantalum due to its very high melting point of over 3,000 degrees Celsius.