Kevlar-based artificial cartilage mimics the magic of the real thing

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 “Kevlartilage” was developed by researchers at the University of Michigan and Jiangnan University.

“We know that we consist mostly of water—all life does—and yet our bodies have a lot of structural stability,” said Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering at U-M, who led the study. “Understanding cartilage is understanding how life .forms can combine properties that are sometimes unthinkable together.”

Many people with joint injuries would benefit from a good replacement for cartilage, such as the 850,000 patients in the U.S. who undergo surgeries removing or replacing cartilage in the knee.

While other varieties of synthetic cartilage are already undergoing clinical trials, these materials fall into two camps that choose between cartilage attributes, unable to achieve that unlikely combination of strength and water content.

The other synthetic materials that mimic the physical properties of cartilage don’t contain enough water to transport the nutrients that cells need to thrive, Kotov said.

Meanwhile, hydrogels—which incorporate water into a network of long, flexible molecules—can be designed with enough water to support the growth of the chondrocytes cells that build up natural cartilage. Yet those hydrogels aren’t especially strong. They tear under strains a fraction of what cartilage can handle.

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 vests—with a material commonly used in hydrogel cartilage replacements, called polyvinyl alcohol, or PVA.

In natural cartilage, the network of proteins and other biomolecules gets its strength by resisting the flow of water among its chambers. The pressure from the water reconfigures the network, enabling it to deform without breaking. Water is released in the process, and the network recovers by absorbing water later.

This mechanism enables high impact joints, such as knees, to stand up to punishing forces. Running repeatedly pounds the cartilage between the bones, forcing water out and making the cartilage more pliable as a result. Then, when the runner rests, the cartilage absorbs water so that it provides strong resistance to compression again.

By PHYS.ORG

Image Credit: Joseph Xu, Michigan Engineering Communications & Marketing

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About Peter Coffaro 699 Articles
A growth-driven and strategic executive, Peter Coffaro commands more than 20 years of progressive management success within the orthopedic industry. Recognized by MedReps.com as one of the top medical sales influencers in the industry; he has 10 years of combined sales management experience and has held positions as a Director, General Manager and Distributor. Peter has worked for some of the top orthopedic companies in the world - Zimmer, DePuy and Stryker. He is also the founder of OrthoFeed: a popular blog that covers orthopedic news and emerging medical technologies. Peter is a three-time Hall of Fame award winner at Johnson and Johnson and has an extensive background in organizational development, business development, sales management, digital marketing and professional education. Peter holds a B.S. degree in Biology from Northern Illinois University.

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