Are your knees sore and stiff? Development of dream 'artificial cartilage', clinical trial next year

A research team at Duke University in the US has developed 'artificial cartilage' (cartilage replacement) that is much stronger and more durable than human cartilage. [사진=벤자민 윌리(듀크대학교)]

The dream of 'artificial cartilage' has come closer to reality.

A research team at Duke University in the U.S. announced that they have succeeded in developing the world's first hydrogel-based 'artificial cartilage', which is stronger than real human cartilage and has three times greater resistance to abrasion (abrasion). This hydrogel implant 'artificial cartilage' (cartilage replacement) is being made by 'Sparta Biomedical', a medical device manufacturing company, and is being tested on sheep. Accordingly, it is expected that clinical trials on 'artificial cartilage' (cartilage replacement), a new bioimplant, will proceed from next year.

The biomaterial hydrogel that the research team released this time as a final product is much stronger and, in particular, much more durable than the early-stage hydrogel developed a few years ago. Hydrogels are made of polymers (polymers) that absorb moisture. Hydrogel, a hydrophilic polymer material that absorbs water and swells, has high biocompatibility and expands or contracts according to changes in external environments such as temperature and hydrogen ion concentration (pH).

"If things go as planned, clinical trials in humans will begin as early as next April," said Benjamin Wiley, a chemical engineer at Duke University, who is the lead author of the study. In clinical trials, clinical trials are conducted on patients with worn out or damaged knee cartilage to confirm efficacy and safety. Prof. Wiley led the research with Prof. Ken Gall (Mechanical Engineering and Materials Science). According to the research team, knee pain caused by osteoarthritis is caused by the wear and tear of cartilage as we age. It is a very common disease affecting about 867 million people worldwide (about 1 in 6 people). However, these patients take over-the-counter pain relievers, receive physical therapy, and receive steroid injections, but it is difficult to cure them. Because of this, many patients still suffer from knee pain.

The research team reported to academia that in 2020, they succeeded in making a hydrogel that is highly likely to be used as cartilage in the knee that supports two to three times the body weight each time you walk. The research team made a hydrogel from several layers of thin cellulose fibers and a polymer (polyvinyl alcohol). Cellulose fibers act like collagen fibers in human cartilage (natural cartilage), and when stretched, they increase the strength of the hydrogel. In addition, polyvinyl alcohol helps to return to the original state. Because of this, it becomes a gel-like material made up of 60% water, which is elastic yet very strong. The hydrogel-based 'artificial cartilage' made in the laboratory by the research team was 26% stronger in tension and 66% stronger in compression than human cartilage. It is comparable to hanging seven grand pianos from a key chain.

However, in order to use this hydrogel as a bio-implant material, many improvements were needed, such as increasing durability. Instead of freezing and thawing the hydrogel, the research team used a heat treatment called annealing to induce more crystals to form within the polymer network. By increasing the content of crystals, the final product was able to withstand 5 times the tension and about 2 times more than the freeze-thaw method. In addition, the problem of fixing the joint to the joint by increasing the strength by heat treatment and placing it in place has been solved. In addition, after bonding and fixing the hydrogel to the titanium base, it was pressed and fixed in the hole where the damaged cartilage was. As a result, it was able to fix the bone 68% harder than human cartilage. The research team applied the soft, slippery and cushion-like properties of human cartilage to increase resistance to abrasion.

According to the research team, human cartilage is durable, but once damaged, there are no blood vessels, so there is a big limit to its ability to heal. In the United States, osteoarthritis is twice as common as it was 100 years ago. If conservative treatment fails, surgery is required. Surgeons have used methods such as removing loose cartilage, drilling holes to stimulate new cartilage growth, or transplanting healthy cartilage from a donor. However, all of these methods require months of rehabilitation, and some fail over time.

A total knee replacement, which can be taken as a last resort, is a pain reliever. However, artificial joints are not permanent, and you will have to suffer the hassle of having to undergo replacement surgery again. Therefore, if 'artificial cartilage' receives approval from the US Food and Drug Administration (FDA) after clinical trials, it is expected to give great hope to numerous knee arthritis patients. Patients will be able to recover their health by replacing only the cartilage without replacing the entire knee joint.

The results of this study (A Synthetic Hydrogel Composite With a Strength and Wear Resistance Greater Than Cartilage) were published in the international scientific journal ≪Advanced Functional Materials≫ and the science portal 'Eureka Alert' (

By Kim Young-seop, staff reporter

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