The knees’ shock absorbers support our every step but for arthritis sufferers with damaged cartilage movement can cause excruciating pain.

A graduate student in America may have found the answer though. Using 3D technology, Feichen Yang, from Duke University, has bio-printed a suitable replacement for the shock absorbers – called the menisci – using a mix of two biocompatible hydrogels.

Prior to Feichen’s discovery experiments with hydrogel had been disappointing as the material wasn’t strong enough to do the job. When the substance came out of a printer nozzle it would run “all over the place, because they are mostly water,” explained Benjamin Wiley, an associate professor of chemistry at Duke and author on the paper, which is online in ACS Biomaterials Science and Engineering.

“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.

Feichen Yang, a student in Wiley’s lab, mixed a strong and a soft hydrogel to create what is termed a ‘double-network hydrogel’. The team tested the material on a plastic replica of a knee after running it off a $300 3-D printer.

“The two networks are woven into each other,” Yang said. “And that makes the whole material extremely strong.”

Another huge plus is a 3D printer can make bespoke and complex shapes, absolutely key for the production of effective meniscus implants.

“Shape is a huge deal for the meniscus. 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,” Wiley added.