Artificial cartilage comes closer to reality

Scientists have found a way to create artificial replacement tissue that mimics both the strength and suppleness of native cartilage.
Combining two innovative technologies, researchers developed a better recipe for synthetic replacement cartilage in joints.
Articular cartilage is the tissue on the ends of bones where they meet at joints in the body - including in the knees, shoulders and hips.
It can erode over time or be damaged by injury or overuse, causing pain and lack of mobility.
While replacing the tissue could bring relief to millions, replicating the properties of native cartilage - which is strong and load-bearing, yet smooth and cushiony - has proven a challenge.

Materials supple enough to simulate native cartilage have been too squishy and fragile to grow in a joint and withstand loading. Stronger substances, on the other hand, haven't been smooth and flexible enough.

Xuanhe Zhao, assistant professor of mechanical engineering and materials science at Duke university, proposed a theory for the design of durable hydrogels or water-based polymer gels and collaborated with a team from Harvard University to develop an exceptionally strong yet pliable inter-penetrating-network hydrogel.
"It's extremely tough, flexible and formable, yet highly lubricating," Zhao said.
"It has all the mechanical properties of native cartilage and can withstand wear and tear without fracturing," said Zhao.

Zhao and Farshid Guilak, a professor of orthopedic surgery and biomedical engineering at Duke, began working together to integrate the hydrogel into the fabric of the 3-D woven scaffolds.
Researchers compared the resulting composite material to other combinations of Guilak's scaffolding embedded with previously studied hydrogels.
The tests showed that Zhao's invention was tougher than the competition with a lower coefficient of friction.
And though the resulting material did not quite meet the standards of natural cartilage, it easily outperformed all other known potential artificial replacements across the board, including the hydrogel and scaffolding by themselves.
The study was published in the journal Advanced Functional Materials.