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Scientists create artificial knee cartilage that outperforms the real thing

[Aug. 2, 2023: Staff Writer, The Brighter Side of News]

Duke University researchers developed a new gel-based cartilage substitute that is stronger and more durable than natural cartilage. (CREDIT: Creative Commons)

Researchers from Duke University have crafted a gel-based alternative to cartilage that surpasses the strength and durability of the natural counterpart. Nearly one in six adults globally suffers from knee pain due to the gradual degradation of cartilage, termed osteoarthritis.

This innovative gel solution presents an opportunity for patients to sidestep knee replacement surgeries, potentially offering a more effective remedy for knee pain sufferers. Presently, Sparta Biomedical is refining and testing the implant on sheep, with plans for human clinical trials slated for 2023.


During experiments, the hydrogel demonstrated a tensile strength 26% greater than natural cartilage and 66% greater compressive strength. The team successfully overcame several engineering hurdles in designing the implant, especially in securing it to the joint—a challenge previous studies hadn't mastered.

To affix the hydrogel, the team employed a method of cementing it to a titanium base. This base is then firmly anchored into a cavity where the damaged cartilage once resided. Mimicking the slick, cushioned texture of authentic cartilage, the hydrogel presents a more resilient and efficient solution for those plagued by knee pain.


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Many individuals, particularly with advancing age, experience knee pain. This discomfort can stem from various reasons such as injuries, overuse, or medical conditions like osteoarthritis. Globally, osteoarthritis impacts nearly one out of every six adults, accounting for about 867 million affected individuals. This degenerative disease erodes the cartilage that provides padding to bone ends, potentially resulting in persistent pain, inflammation, and rigidity.

There's a range of remedies to mitigate knee pain, from over-the-counter medications and physical therapy to steroid injections. Nevertheless, for some, these solutions may not suffice, making knee replacement surgery a necessary consideration.


Knee replacement surgery involves removing the damaged cartilage and replacing it with an artificial joint made of metal or polyethylene. While this surgery can be successful, it is a major operation that requires months of rehabilitation and can come with risks, such as infection and blood clots.

A hydrogel-based implant could replace worn-out cartilage and alleviate knee pain without replacing the entire joint. (CREDIT: Benjamin Wiley, Duke University)

A new option may soon be available to knee pain sufferers that could provide a less invasive and more effective treatment. Researchers at Duke University have developed a gel-based cartilage substitute that is stronger and more durable than natural cartilage. The team, led by chemistry professor Benjamin Wiley and mechanical engineering and materials science professor Ken Gall, published their findings in the journal Advanced Functional Materials.


The hydrogel is made from thin sheets of cellulose fibers that are infused with a polymer called polyvinyl alcohol. The cellulose fibers act like the collagen fibers in natural cartilage, giving the gel strength when stretched, while the polyvinyl alcohol helps it return to its original shape. The resulting material is a Jello-like substance that is 60% water but is surprisingly strong.

A Synthetic Hydrogel Composite with a Strength and Wear Resistance Greater than Cartilage. (CREDIT: Advanced Functional Materials)

The researchers found that the hydrogel can be pressed and pulled with more force than natural cartilage and is three times more resistant to wear and tear. Natural cartilage can withstand up to 8,500 pounds per inch of tugging and squishing before breaking, while the lab-made version can handle even more. It is 26% stronger than natural cartilage in tension and 66% stronger in compression.


In addition to being stronger, the hydrogel mimics the smooth, slippery, cushiony nature of real cartilage, protecting other joint surfaces from friction as they slide against the implant. The researchers tested the implant's wear over time by spinning artificial cartilage and natural cartilage against each other a million times, with a pressure similar to what the knee experiences during walking.

Using a high-resolution X-ray scanning technique called micro-computed tomography, the scientists found that the surfaceof the implanted cartilage remained smooth and intact after the million rotations, indicating that it had minimal wear and tear.

The researchers were thrilled with the results of their testing, as it suggested that the implant could potentially last for many years without needing to be replaced. However, they knew that further testing would be necessary to confirm their findings and to ensure that the implant was safe and effective for use in humans.

To this end, the team began planning a series of animal studies to evaluate the implant's long-term safety and effectiveness. They also began exploring potential partnerships with medical device companies to help bring their technology to market and make it available to patients in need.

As news of the breakthrough spread, the research team received numerous accolades and awards for their work. They were even invited to present their findings at international conferences and symposia, where they shared their insights with other researchers and medical professionals.


Despite the recognition they received, the researchers remained focused on their ultimate goal: to develop a safe and effective implant that could help improve the lives of people with knee osteoarthritis. And with each new study and experiment, they came one step closer to achieving that goal.

For more science news stories check out our New Innovations section at The Brighter Side of News.


Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.


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