I did some post-grad work doing this 6 years ago now; we were able to custom print out artificial knees/hip implants that were made of a calcium polyphosphate (aka, CPP; a porous, artificial bone-like material), titanium, and stem cells.
The idea is that when implanted, the surrounding bone would grow into the porous CPP, slowly dissolving the CPP and replacing it over time. The titanium internal structure of the implant, potentially porous also, would remain afterwards for added strength that the natural bone would eventually affix strongly too.
The stem cells were being used on top of the CPP to grow a cartilage-like layers that are needed for the knee to function smoothly. Otherwise you might get arthritis.
That was all along time ago for me though now and it was all in the testing stages. Give it another 20 years; we will be growing bodies I tell ya!