Artificial Cartilage Gel May One Day Treat Damaged Knees
On average, more than 790,000 knee replacements happen in the United States every year, and currently, those replacements involve invasive surgery. After going through such an invasive process, these knee replacements may only last for a couple of decades before they need to be replaced again.
Given the unique properties of hyaline cartilage, it's no surprise that scientists have had a difficult time trying to develop an artificial substitute. Natural knee cartilage is both a superior cushion and a tough barrier to protect the joint from injury. It looks like researchers made a significant breakthrough when they finally developed a material that is as strong as the cartilage found in the body and could be used as a replacement after injuries or when people age.
Chemist Ben Wiley of Duke University said, "We set out to make the first hydrogel that has the mechanical properties of cartilage." The main ingredients of this material include water-absorbing polymers. In the case of the artificial cartilage, the polymers are made of spaghetti-like strands, intertwined with another polymer that is less flexible and more basket-like.
A third polymer that is made of cellulose fibers, acts as a mesh holding the two other polymers. When the material is stretched, it is the third polymer that keeps the gel intact. But when the material is squeezed, the first two polymers with negative charges along their length repel each other and stick to water, so the material goes back to its original shape.
The hydrogel passed with top marks in the categories of stretching and squishing and showed better performance than other existing hydrogels. It was able to hold up during a test of 100,000 cycles.
According to materials scientist Feichen Yang, also from Duke University, only the combination of all three components is both flexible and stiff, making the material strong. They also tested the hydrogel by rubbing it against like the natural cartilage for more than a million times. The hydrogel has also shown to be just as resistant to wear and tear as the real thing.
However, according to researchers, it could take up to three years before this new hydrogel can be approved for use in humans. So, there is still some way to go before it can be used on patients who need knee replacements. They have only tested the non-toxicity of the material on lab-grown cells. When it can be safely transplanted into an animal, only then can trials on humans begin.
The new material shows a lot of promise as an option for those experiencing knee replacement surgeries that may one day be able to restore a joint to its full working order without a long recovery period. It should also help until the cartilage regrows.
The researchers published their study in the journal Advanced Functional Materials.