3D print your way to a perfect implant Jakus et al

Who would have thought a plain white ink could transform bone surgery? The newly developed ink can be used to 3D-print flexible bone implants in any size, shape and form – from cylindrical leg bones to entire skulls. What is more, once inside the body, the implants turn into real bone, giving surgeons a cheap and versatile way of repairing an injury.

When bones need to be fixed or replaced, doctors tend to take bone from other parts of the body, or use implants. Although the less painful option, implants are often brittle, meaning they break easily and can’t be remodelled during surgery. Another option is to use putties made from crystallised bone of variable quality that come from human cadavers – but this is expensive.

Now, Ramille Shah at Northwestern University in Evanston, Illinois, and her colleagues have developed an ink that can be 3D-printed into bone implants that are robust but ultra-elastic, allowing surgeons to cut and manipulate them in the operating theatre to form the perfect shape.


Once in place, the implants are rapidly infiltrated by blood vessels and gradually turn into natural bone. Shah’s team calls the implant material “hyperelastic bone” and says it could heal a multitude of skeletal problems, from fractures and spine repairs to implants that help to rebuild faces after injury or chemotherapy.

Custom implants

“Our vision is to have 3D printers in a hospital setting where we provide the hyperelastic bone ink, so surgeons can make individual implants within 24 hours,” says Shah. “You could make off-the-shelf, or patient-specific implants using scans from patients,” she says.

The ink is made from hydroxyapatite, a mineral found naturally in bone, and PLGA, a polymer that binds the mineral particles together, and gives the implants their elasticity. “We were very surprised to find when we squeezed an implant, it bounced back to its original shape,” says Shah.

Adam Jakus, also at Northwestern, believes that the implants so closely mimic natural bone in their pore structure and mineral content, that the body’s repair processes mistake it for incomplete bone that needs remodelling to bring it back to perfection.

In tests, the implants healed spinal defects in rats as fast and as well as existing treatments. The team also made an implant to heal an area of damaged skull in a rhesus macaque. It started out too big, but surgeons were able to cut it to exactly the right shape in the operating room. Shah says the material should reach the clinic within five years.

“It’s terrific, and a great advance,” says Iain Hutchison, a maxillofacial surgeon at St Bartholomew’s Hospital in London. “They’ve created a matrix, not a bone, and it seems they can grow bone on it without having to add stem cells or other growth factors,” he says.

Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.aaf7704