WHY THIS MATTERS IN BRIEF
Hydrogels are proving to be an amazingly versatile material, and in this case they could help revolutionise how surgeons treat knee conditions and injuries.
A new cartilage-like hydrogel material could make the job of repairing knees much easier, say a team of scientists in the US, and the fact that the new material can be 3D printed means that it can be used to create implants that are exact fits for a patients knee.
The teams new research focused on the two crucial shock absorbers inside the knee, known as the menisci, and replacing these parts of our bodies needs both the right material properties and the right shape, get either wrong and at best the treatment won’t work and at worst it’ll inflame the area and cause the patient huge amounts of pain. And that’s the challenge the scientists from Duke University took up and after just one day’s work they’d created a suitable, 3D printed, hydrogel meniscus with a cost point of less than $300.
You have to admit that’s impressive… and if their feat can be replicated on a larger scale then doctors everywhere could be looking at simple and inexpensive knee repairs for what are usually complex and problematic injuries.
“We’ve made it very easy now for anyone to print something that is pretty close in its mechanical properties to cartilage, in a relatively simple and inexpensive process,” said Benjamin Wiley who led the research.
Each of our knees has two ear shaped menisci, sitting between the thigh and shin bones, that cushions every step we take. If these supports get damaged, walking becomes painful and the risk of arthritis increases.
When we reach adulthood, these menisci can’t really heal themselves, and broken ones often have to be replaced by surgeons. The trouble is, today’s implants aren’t as strong or elastic as the real thing, or do nothing to aid healing around the knee.
What’s more, the meniscus is made up of two complementary layers – a stiff middle and a soft outer layer – which complicates attempts to develop something that can be 3D printed from just a single material.
To get around this the team combined both a strong hydrogel and a stretchable hydrogel together to try to get a material as close to cartilage as possible. They also added a nanoparticle clay to make the substance runny under stress but quick to harden.
“The two networks are woven into each other,” explains another member of the team, Feichen Yang, “and that makes the whole material extremely strong.”
Scientists are warming up to the idea of using hydrogels like these as cartilage replacements, because they share certain properties – take a close look at either, and you’ll see a web of long string-like molecules with water molecules wedged in between, but that said there are also other companies out there now who have discovered how to 3D print real cartilage so the race to revolutionise knee treatments, as well as other joint treatments, is hotting up.
Plus, as we know from other research, the beauty of 3D printing in medical health is that replacement body parts, from brain, heart and kidney tissue to bone and skin, can be made to order, just the right size and shape for a patient, and that’s particularly important here too.
“Shape is a huge deal for the meniscus,” adds Wiley, “this thing is under a lot of pressure, and if it doesn’t fit you perfectly it could potentially slide out, or be debilitating or painful.”
Using Computer Tomography (CT) or Magnetic Resonance Imaging (MRI) scans, which in themselves might one day be revolutionised thanks to a recent magnetic wormhole discovery, doctors can work out how implants need to be designed and then feed that information into a 3D printer, as long as, that is, we have artificial materials that can do as good a job as natural ones.
The researchers admit it’s early days for this “young field” of research, but the menisci demo shows the potential of hydrogels to simplify knee repairs.
We now know it’s possible to develop hydrogels with similar properties to cartilage that can also be created and manipulated with a budget 3D printer, and with more study, printable materials even closer to human tissue could be developed on day.
“I hope that demonstrating the ease with which this can be done will help get a lot of other people interested in making more realistic printable hydrogels,” says Wiley.
The research has been printed in ACS Biomaterials Science and Engineering.
