Researchers studying kangaroo cartilage found that it may help in engineering better artificial knee and shoulder joints for humans. Cartilage, that flexible connective tissue found between bones that helps them move without pain, does not easily repair itself when it degrades. To fix this, artificial joints are implanted, but even they have their limits. Scientists from the Queensland University of Technology in Australia turned to studying the shoulder cartilage of kangaroos.

"Knee cartilage has been studied extensively. However, there are only limited studies specifically focusing on shoulder cartilage tissues. We think [studying shoulder cartilage] is important, because, especially in sports activities, there is a possibility that the shoulder may get affected by injuries and eventual osteoarthritic development," Yuantong Gu, lead researcher and professor at the Queensland University of Technology, said in a news release.

Osteoarthritis occurs over time as the cartilage on the ends of your bones wears away. It is the most common form of arthritis. The kangaroo was chosen as a suitable model for human comparison, since it moves using its two rear limbs, is similar in size, and has upper arm movements similar to humans', as the release noted. 

The scientists deformed the kangaroo cartilage by preforming a "indentation test," which involved their pressing a rounded rod into the tissue and adding enzymes to deteriorate specific components. From this, they found at the surface of the cartilage  a network of collagen proteins that helped absorb the inflicted forces without causing damage.

This means that artificial cartilage needs to be custom engineered to a specific shoulder or knee joint, so that it mimics the different movements that the tissues are subjected to within particular joints, Gu noted. 

"We hope to improve the design and manufacture of artificial cartilage materials by applying our improved understanding of the key factors that contribute to the biomechanical properties of the natural cartilage," he said.

Their findings were published in the journal Applied Physics Letters

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