Natural cartilage plays an important role in the joints. It absorbs shocks and allows movement. But this material degrades over time and can cause problems, especially in the elderly. Cartilage doesn’t regenerate very well either. To enable people with weakened cartilage to regain their mobility, Duke University researchers have developed a new hydrogel stronger than natural cartilage. This hydrogel can be used to make more durable knee implants.
Hydrogels are flexible and soft materials. They have already been considered a potential alternative to natural cartilage. However, until now, the hydrogels created were too weak to be able to support a heavy weight. The hydrogel created by Duke University scientists in 2020 has on its side properties similar to those of natural cartilage. An even better version of the latter is also being developed.
Currently, knee treatment options are limited to pain medication, physical therapy, or total reconstruction. With the hydrogel developed by Duke researchers, a better option may soon be available.
The characteristics of the new hydrogel
The new hydrogel was made from cellulose fibers. This makes it more durable when stretched. The researchers also used polyvinyl alcohol which allows the material to return to its original shape. Additionally, the team changed the manufacturing process. Instead of freezing and then melting, as is the case with most hydrogels, they decided to anneal the material like glass, which produces more crystals in the polymer network.
With this modified process, the researchers obtained a hydrogel with a tensile strength of 51 MPa and a compressive strength of 98 MPa. Compared to natural cartilage, its tensile strength is 26% higher while its compressive strength is 66% higher.
In another test, the researchers used a machine to rub the artificial cartilage against natural cartilage a million times, with similar pressure to what exists in the knee. The results showed that the hydrogel was 3 times stronger than natural cartilage.
The method of implantation
Scientists know that it is difficult to attach the hydrogel to the bone in the knee joint. Therefore, they also tested a way to solve this problem. The artificial cartilage was cemented and clamped to a titanium base which will be fixed at the level of the hole left by the damaged cartilage. This configuration demonstrated a shear strength of 2 MPa, which is 68% higher than the grip of natural cartilage on the bone.
According to the scientists, they are currently testing the implants with the hydrogel on sheep. Clinical trials on humans will begin in April 2023.