Don't you hate when you run out of bone? It's sort of a necessary component to staying alive, yet if you bash it up wrong or don't take care of it in the long run you might find yourself without enough of it. Doctors have been able to supplement skeletons with metal in the past, but it's not really a substitute for the real thing. Now that we've got a bone printer in the world, though, osteoporosis and other bone disorders don't seem quite so daunting anymore.

Researchers at Washington State University have hacked a commercially available 3D printer for bone-making purposes. 3D printers are typically used to construct things out of plastic, metal or other materials, but a newly invented compound allows the printer to create a scaffold on top of which new bone cells can grow. The printer sprays a plastic binder over the compound, a silicon, zinc, and calcium phosphate powder. After many thin layers are applied, the process produces a small cylinder. When the cylinder is immersed in a solution containing immature bone cells, it serves as a scaffold for new bone growth. 

The process isn't quite as immediate as clicking a button and printing out a new femur. The scaffold has to sit in bone goo for about a week before it acquires a network of brand new bone cells. Once the scaffold is inserted into living bone, the new cells continue to grow. It hasn't yet been tested on humans, but initial in vivo tests on rats and rabbits have proven to be effective. The original scaffold even dissolved on its own in time, meaning new bone growth without negative side effects may be possible. 

This is great news for people whose skeletons aren't quite what they used to be. Doctors will be able to take a CT scan of a particular bone defect and then have technicians create a custom scaffold for that particular defect. It's a pretty awesome feat of chemical engineering made possible by the discovery that silicon and zinc significantly increase the strength of calcium phosphate when combined with it. 

It seems like we're finding ways to create artificial body parts everywhere we look. We're a long way off from printing whole skeletons using just a 3D printer, but it's still pretty 21st century to say that we can just grow new bone tissue from an existing set of cells using a synthetic scaffold.