3D-printed bones? New 'hyperelastic' material could let doctors print implants on demand

Researchers at Northwestern University develop a new 3D-printable synthetic bone that could one day could help transform major surgery.
Written by Liam Tung, Contributing Writer

The hyperelastic bone opens the possibility that hospitals may be able to use an inhouse 3D printer to build custom implants on demand.

Image: Science Translational Medicine/Northwestern University

Researchers have developed a synthetic 'hyperelastic bone' that can be customized using a 3D-printer and implanted in the body to mend damaged bones.

The flexible bone-grafting material not only supports broken bones but in tests on animals was found to promote bone growth around the structure, according to new research published in Science Translational Medicine.

The material, developed by a team of researchers at Northwestern University, acts as both structural support and a kind of scaffold for bone regeneration. Also, lab rats didn't reject the material, which makes it a promising aid to conventional treatments, such as metal plates and rods, for fractured arms and other bone repair surgery.

While both adult and children patients may benefit from the hyperelastic bone (HB), the researchers said it will have a greater impact where metallic implants are used to treat bone defects in children, since these implants often need to be replaced as the child's body grows.

"Adults have more options when it comes to implants," said Ramille N Shah, HB's lead researcher. "Pediatric patients do not. If you give them a permanent implant, you have to do more surgeries in the future as they grow. They might face years of difficulty."

HB is composed of mostly of hydroxyapatite in ceramic powder form blended with a polymer called polycaprolactone. Hydroxyapatite is a mineral form of calcium found in human teeth and bones that is currently used in bone grafting, while the polymer, which also has biomedical applications, is popular for product prototyping, because it's hard when cold but malleable at 60C.

Key challenges that the researchers say it overcomes are cost and the speed of producing customized support structures, thanks largely to the elasticity added to hydroxyapatite's bone-regeneration qualities.

"Cells can sense the hydroxyapatite and respond to its bioactivity. When you put stem cells on our scaffolds, they turn into bone cells and start to upregulate their expression of bone specific genes," Shah said.

"This is in the absence of any other osteo-inducing substances. It's just the interaction between the cells and the material itself."

Shah also noted that the 3D-prints could be incorporated with antibiotics or combined with other materials that encourage growth.

Physicians will be able cut out patches of the material if printed in sheet form, or take a scan of a patient's body to print a custom bone. Additionally, the material can also be printed at room temperature, and used almost immediately after printing, opening the possibility that hospitals may be able to use an inhouse 3D printer to build custom implants on demand.

"The turnaround time for an implant that's specialized for a customer could be within 24 hours," Shah said. "That could change the world of craniofacial and orthopaedic surgery, and, I hope, will improve patient outcomes."


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