US researchers have developed a new material which could be used as an implant to replace a torn or damaged meniscus.
According to Duke University, the hydrogel-based material is unique in that it matches human cartilage in strength and elasticity while also remaining 3D-printable and stable inside the body.
The menisci are rubbery cushions that lie in the knee between the major bones of the joint, acting like shock absorbers. They can become damaged during sports or simply from a lifetime of wear-and-tear.
As Duke University explains, the meniscus has limited ability to heal on its own. If it cannot be repaired in keyhole surgery, surgeons may partially or completely remove the damaged meniscus.
However, available implants either do not match the strength and elasticity of the original cartilage, or are not biocompatible. This means they do not support the growth of cells to encourage healing around the site.
Hydrogels are biocompatible and share a very similar molecular structure to cartilage, but researchers have struggled to find a formula that is equal in strength to human cartilage or is 3D-printable.
“The current gels that are available are really not as strong as human tissues, and generally, when they come out of a printer nozzle they don’t stay put — they will run all over the place, because they are mostly water,” explained Benjamin Wiley, an associate professor of chemistry at Duke and co-author of the study, which has been published online in ACS Biomaterials Science and Engineering.
Feichen Yang, a graduate student in Wiley’s lab and another study co-author, experimented by mixing together two different types of hydrogels — one stiffer and stronger, and the other softer and stretchier — to create what’s known as a double-network hydrogel. By changing the relative amounts of the two hydrogels, Yang created an extremely strong material with a strength and elasticity similar to human cartilage.
Another ingredient, a nanoparticle clay, makes it possible to produce the synthetic cartilage with a 3D printer.
“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,” Wiley said.