This artificial cartilage gets its strength from the stuff in bulletproof vests

A new kind of artificial cartilage, made with the same kind of fiber that fortifies bulletproof vests, is proving stronger than others.

The fabricated material mimics the stiffness, toughness and water content of natural cartilage, researchers report in the Jan. 4 Advanced Materials. This synthetic tissue could replace the cartilage in a person’s body that naturally wears down and heals poorly (SN: 8/11/12, p. 22), alleviating joint pain and potentially sparing many people from having to undergo joint replacement surgery.

Scientists have been trying to fashion artificial cartilage for decades, says Kara Spiller, a biomedical engineer at Drexel University in Philadelphia not involved in the work. But earlier materials were either weaker than the real thing or didn't pack enough water to transport nutrients to surrounding cells.

The new material is a polymer mixture called a hydrogel that’s mostly water and contains nanoversions of the aramid fibers used to make bulletproof vests. Nicholas Kotov, a chemist at the University of Michigan in Ann Arbor, and his colleagues tested how well their material held its shape when squeezed or stretched, and how easily it was broken. Both versions of the hydrogel — one, about 70 percent water; the other, about 92 percent water — either matched or exceeded the stiffness and toughness of real cartilage.

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Sturdy stuff

This up-close electron microscope view shows the nanofiber and polymer network that composes a new kind of synthetic cartilage and gives this water-based material its strength.

The new material has “a lot of different possibilities,” Spiller says. “The biggest market is going to be osteoarthritis patients, because most patients with osteoarthritis have no damage to the bone, just damage to the cartilage.” Many of the 30 million adults in the United States who suffer from osteoarthritis undergo whole knee or hip replacements. If doctors could simply replace worn down cartilage with this material, that could lower the risk of surgical complication. “That would be really huge,” Spiller says.

This kind of hydrogel “could also be used for all sorts of sports injuries, where you have damaged tendons or ligaments, [or] even for back pain,” she adds.

It remains to be seen how well this material can integrate into a person’s body, says Benjamin Wiley, a chemist at Duke University not involved in the work. Researchers still need to make sure it can anchor to bone and doesn’t irritate surrounding tissue.