Worn out cartilage in the knees is a major cause of disability and once it’s worn out there’s nothing ideally suited to replace it. Osteoarthritis develops,and eventually much of the entire knee is often replaced, with variable success. Researchers at Duke University have been working on creating a material that can serve as a cartilage replacement and they have already developed something at least as strong and pliable as the cartilage making up the knee’s meniscus.
Moreover, the material can be used inside a cheap 3D printer to create the exact shape desired, opening the possibility that we’ll be seeing 3D printers in orthopedic operating rooms in the not too distant future.
The team’s material is a novel hydrogel that is stronger than previously developed hydrogels and even stronger than natural meniscus cartilage, yet having the elasticity of cartilage. This was thanks to a careful combination of two different hydrogels that have somewhat opposite characteristics. One is strong and the other soft and pliable, and the two hydrogels are essentially “woven” into each other, according to the researchers.
The hydrogel mix can be adjusted to create just the right amount of strength and flexibility desired for different applications. Mixing in a special “nanoparticle clay” gives the material the quality of turning to liquid under pressure and back to a solid when the pressure is removed.
This is an ideal feature for 3D printing, as the pressure inside the needle of the printer is high enough for the material to remain a liquid. As soon as it is deposited by the printer, it turns to a solid and becomes part of the object being built.