A Duke University-led team said they have created the first gel-based cartilage substitute that is even stronger and more durable than the real thing. Mechanical testing reveals that the team’s hydrogel—a material made of water-absorbing polymers—can be pressed and pulled with more force than natural cartilage and is 3-times more resistant to wear and tear. Implants made of the material are currently being developed by Sparta Biomedical and tested in sheep. Researchers are gearing up to begin clinical trials in humans next year.
To make this material, the team took thin sheets of cellulose fibers 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, giving the gel strength when stretched. The polyvinyl alcohol helps it return to its original shape. The result is a Jello-like material, 60% water, which is supple yet surprisingly strong.
Natural cartilage can withstand 5,800 to 8,500 pounds per inch of tugging and squishing, respectively, before reaching its breaking point. This lab-made version is the first hydrogel that can handle even more. It is 26% stronger than natural cartilage in tension, something like suspending 7 grand pianos from a key ring, and 66% stronger in compression, which would be like parking a car on a postage stamp.
Their method of attachment involves cementing and clamping the hydrogel to a titanium base. This is then pressed and anchored into a hole where the damaged cartilage used to be. Tests show the design stays fastened 68% more firmly than natural cartilage on bone.
