One company, FibreTuff is compounding a cellulose-based biomaterial for 3D rinting and molding of medical devices for spine, trauma and sports medicine. 
One major benefit to the material is that it can be seen on x-rays without the introduction of additives a term known in medical circles at radio-opaque. 3D bone replacements are similar in weight an composition to actual bone and will not dissolve inside the body. 
The compounded product (cellulose-based PAPC) is produced as a filament for 3D printers and also as pellets and bar stock for injeciton molding, extrusion and machining.