A new type of hydrogel is coming to replace damaged knee cartilage

A new type of hydrogel is coming to replace damaged knee cartilage

Developed by American researchers, it is much stronger than natural cartilage and three times more wear resistant.

Those who suffer from pathologies affecting the articular cartilages, and in particular that of the knee, know well how difficult it is to live with pain, swelling and difficulty in movement. In some cases, these symptoms result from the progressive wear and tear of the cartilage, a condition known as osteoarthritis affecting nearly one in six adults worldwide, for which current treatment options include drug therapies, physiotherapy and surgery. For those who want to avoid replacing the entire joint, however, there may soon be another option, developed by a research team at Duke University in Durham, North Carolina, which has created the first hydrogel-based cartilage substitute with properties similar to those of natural cartilage.

Hydrogels are materials flexible and soft, and have already been considered as a potential alternative to natural cartilage. However, until now, these materials have proved too weak to be able to support a high weight, limiting their possible use. The hydrogel developed by Duke University researchers has instead proved to be much stronger than natural cartilage and three times more wear resistant, thanks to an innovative production process. To make it, the team used cellulose fibers and infused them with a polymer called polyvinyl alcohol, a sticky, viscous substance that allows the material to return to its original shape.

As mentioned, the researchers also developed a new manufacturing process, whereby, instead of freezing and then thawing to produce crystals inside the gel – as is the case with most hydrogels – they used a heat treatment called annealing to favor the formation of a greater number of crystals within the polymeric network. By increasing the crystal content, the researchers were able to produce a gel that can withstand five times greater stress when pulling and almost twice squeezing compared to freeze-thaw methods. The increased resistance also helped resolve a second design challenge, i.e. fixing the hydrogel to the joint with sufficient force to prevent it from loosening or slipping away.

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The first implants made with this material are currently in the pre-clinical trial phase and, if all goes according to plan, human testing should begin in April 2023, as explained by Professor Benjamin Wiley of Duke University who led the research together with engineer Ken Gall.

The production approach, the scholars specify in a study published in the journal Advances Functional Materials, made it possible to obtain a hydrogel with a tensile strength of 51 megapascals (MPa) and a compressive strength of 98 MPa. Compared to natural cartilage, this results in 26% higher tensile strength and 66% higher compressive strength.

In another test, the researchers used a machine to assess the wear of artificial cartilage that rubs against natural cartilage a million times, with similar pressure to that exerted in a knee, showing the hydrogel. it is three times stronger than natural cartilage . “Its strength is truly off the charts – commented Wiley -. Because the hydrogel mimics the smooth, slippery, and mushy nature of natural cartilage, it also protects other joint surfaces from friction as they rub against the implant.“.


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