The rigidity of bones is what allows us to walk upright, instead of slithering like a pile of goo on the floor: a homo sapiens blobfish. But that rigidity has a price. When it can't handle the strain anymore, a bone doesn't deform, it breaks. And when it does, you need a cast if it's a simple break—or even reconstructive surgery, if it's a bad one where pieces of skeleton have been obliterated.
When it comes to medically 3D-printed replacements, though, the future of skeletons isn't rigid. It's squishy. A new technique imagines that when we break bones badly in the future, we'll support them with a squishy 3D-printed scaffold. In bad breaks, this scaffold will let our bones mend themselves straight, but also give them some slight ability to bend without knocking the fracture out of alignment.
Created by a team at Northwestern University in Chicago, this new material, which its inventors called "hyperelastic bone," is made from an elastic polymer and hydro calcium minerals, like those found in human bones and teeth. Once embedded in the body, hyperelastic bone works as a bridge between actual bones, promoting blood flow between fractured segments . . . which, in turn, causes it to be ossified over time with newly formed bone.
The scaffolding is strong, too. Hyperelastic bone can support up to 150 pounds without breaking, and that's without a coating of newly-grown bone to make it stronger. It's also fast for doctors to print: A relatively simple 3D printer can print out a 42-square-inch segment of the stuff in just an hour. This makes it cheaper and more useful than other bone replacement and grafting materials doctors use, such as calcium phosphate, a ceramic-like material that is so brittle, it can be hard to get bone to grow on it.
Since implementing it requires an invasive procedure, hyperelastic bone isn't likely to be used for simple stress fractures. But for bad breaks, it could be revolutionary. Indeed, the researchers were able to help a rhesus macaque recover from a serious skull fracture in just eight weeks—all without any negative immune system responses.
It's just the latest example of how 3D printing is changing medicine—not only helping us heal bones faster, but targeting diseases like cancer. Hyperelastic bone isn't likely to make breaking a bone any less pleasant, true. But if you do end up with a bad break, at least you won't be forever doomed to set off alarms when you walk through airport security.