The artificial cartilage is very flexible yet resistant to tearing. (Credit: Joseph Xu, Michigan Engineering)

The unparalleled liquid strength of cartilage, which is about 80 percent water, withstands some of the toughest forces on our bodies. Synthetic materials couldn’t match it — until the development of Kevlartilage.

The new Kevlar-based hydrogel recreates the magic of cartilage by combining a network of tough nanofibers from Kevlar — the aramid fibers best known for making bulletproof vest — with a material commonly used in hydrogel cartilage replacements, called polyvinyl alcohol, or PVA.

Like natural cartilage, the synthetic cartilage releases water under stress and later recovers by absorbing water like a sponge. The aramid nanofibers build the framework of the material, while the PVA traps water inside the network when the material is exposed to stretching or compression. Even versions of the material that were 92 percent water were comparable in strength to cartilage, with the 70-percent version achieving the resilience of rubber.

The aramid nanofibers and PVA don't harm adjacent cells. The researchers anticipate that the synthetic cartilage may be a suitable implant for some situations, such as the deeper parts of the knee. Potential applications are not limited to cartilage. Similar networks, with different proportions of aramid nanofibers, PVA and water, may be able to stand in for other soft tissues.