Health

3D-printed 'elastic' bones could heal fractures and revolutionise reconstructive surgery

A hyperelastic bone in the shape of a section of the human spine 3-D printed using an ink developed at Northwestern University. Credit Adam E. Jakus

Northwestern University researchers think found an elegant solution to this complex medical intervention: 3-D print new artificial bones. Surgeons successfully used the substance to fuse the spines of rats and fix a skull defect in a monkey, the researchers reported today in Science Translational Medicine. "There is actually evidence of new bone formation". Besides being safe and efficacious, that is, allowing regeneration and not setting an immune response, such material should be easy to use in the operating room. The findings were reported in Science Translational Medicine.

Ramille Shah, a professor in Northwestern University's Department of Materials Science and Engineering, helped develop the technology and sees many applications for it.

This new material, known as a "hyperelastic bone", appears and acts like a human bone inside the body.

The researchers placed humans stem cells into scaffolds that were 3D printed from the hyperelastic bone material.

Both hydroxyapatite and PLGA, Jakus told reporters, are "established materials". They also wanted to make a material that didn't need to be cured by heat.

However, Jakus said, individually, the components "work, but they have not been shown to work fantastically". In weight, its contents are 90% hydroxyapatite, which should make it very brittle, and yet it can be squeezed and stretched and still recover. No growth factors are used to stimulate healing. Niklason particularly noted the team's experiment in which a monkey with thinning patch of skull received a graft of hyperelastic bone.

"Our 3-D structure has different levels of porosity that is advantageous for its physical and biological properties", he said.

Cells can sense the hydroxyapatite and respond to its bioactivity. It could also be useful when repairing bones that are injured or deformed, according to NBC News and the Los Angeles Times.

"The turnaround time for an implant that's specialized for a customer could be within 24 hours", Shah said. "And this was just because of the material", Jakus said. They're often really stiff, which makes it hard for a surgeon to modify the implant without breaking it.

The team's insight came from the idea of combining materials used in bioengineering with production approaches from industry, says Jakus, who has an academic background in metallurgy and explosive materials.

The synthetic bones also grow with the patient, meaning they could prevent children with skeletal problems from having multiple surgeries to replace ill-fitting grafts. It is not flexible, and if surgeons want tomodify the implant, they have to break it.

That improved the microstructure of the ink, says Shah. "That way, we can identify anything we need to tweak", she said.

"There are a lot of pediatric patients, especially in third world countries, who are born with orthopedic or Maxillofacial (face and jaw bone) defects", Shah added, according to Yahoo News.

In tests, the implants healed spinal defects in rats as fast and as well as existing treatments.

"And we hope that because the Hyper-Elastic Bone is scalable and at a lower cost, that it would be accessible to those types of patients".

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3D-printed 'elastic' bones could heal fractures and revolutionise reconstructive surgery