Perhaps I'm too credulous, but each advance in 3D printing for medical/surgical applications leaves me agog: http://mashable.com/2016/02/25/3d-printed-vertebrae-spine/#Og0jman9_kqk.
I wonder how long printed replacement parts will last? I know that some hip transplants have to be redone after X number of years. How do we know whether patients might be allergic to substances used to print the parts?