New York, Aug 14 : Do you suffer from stiff, achy knees and are tired of over-the-counter pain relievers, physical therapy, steroid injection but don't want to replace the entire knee joint? Take heart, a novel gel-based cartilage substitute that is even stronger and more durable than the real thing has been developed. The hydrogel -- a material made of water-absorbing polymers -- can be pressed and pulled with more force than natural cartilage, and is three times more resistant to wear and tear, according to a team from Duke University in the US. Natural cartilage can withstand a whopping 5,800 to 8,500 pounds per inch of tugging and squishing, respectively, before reaching its breaking point. But the lab-made version is the first hydrogel that can handle even more. It is 26 per cent stronger than natural cartilage in tension, something like suspending seven grand pianos from a key ring, and 66 per cent stronger in compression -- which would be like parking a car on a postage stamp, the team wrote in the journal Advanced Functional Materials. Implants made of the material are currently being tested in sheep. Researchers are gearing up to begin clinical trials in humans next year. "If everything goes according to plan, the clinical trial should start as soon as April 2023," said Duke chemistry professor Benjamin Wiley, who led the research. Knee pain comes from the progressive wear and tear of cartilage known as osteoarthritis, which affects nearly one in six adults -- 867 million people -- worldwide. To make this material, the team took thin sheets of cellulose fibres and infused them with a polymer called polyvinyl alcohol -- a viscous goo consisting of stringy chains of repeating molecules -- to form a gel. The cellulose fibers act like the collagen fibers in natural cartilage, Wiley said -- they give the gel strength when stretched. The polyvinyl alcohol helps it return to its original shape. The result is a Jello-like material, 60 per cent water, which is supple yet surprisingly strong. /IANS