Some people are still dealing with knee pain after trying all sorts of remedies.
Osteoarthritis affects nearly one in six adults and is the leading cause of knee pain around the world. It may soon be possible for patients to get back on their feet fast and not have to have a knee replacement.
A Duke University-led team says they have created the first gel-based cartilage substitute that is even stronger and moredurable than the real thing.
The Duke team's material is three times more resistant to wear and tear and can be pressed and pulled with more force than other materials.
Sparta Biomedical is currently testing the implants in sheep. Next year will see the start of human clinical trials.
"If everything goes according to plan, the clinical trial should start as soon as April 2023," said Duke chemistry professor Benjamin Wiley, who led the research.
In order to make this material, the Duke team took thin sheets of cellulose fibers and infused them with a sticky substance called polyvinyl alcohol.
The gel strength is given by the gel strength of thecellulose fibers. It gets back to its original shape with the help of alcohol. The result is a Jello-like material which is surprisingly strong.
It can hold up to 8,500 pounds per inch of tugging and squishing before it breaks. The lab-made version is able to handle more. It is 26% stronger than natural cartilage in tension, something like suspending seven grand pianos from a key ring, and 34% stronger in compression.
It is off the charts in terms of strength.
The team has made amazing things. The first hydrogel that felt the force of two to three times body weight was created in 2020.
Design challenges were presented when the gel was put to practical use. The other was reaching the upper limits of the strength of the cartilaginous tissue. About 1,400 pounds per square inch is the amount of pressure on the knee caused by jumping, lunging, and climbing stairs. The tissue can be four times larger before it breaks.
There was room for improvement.
In the past, researchers used a freeze-thaw process to make crystals within the gel, which drive out water and help hold the chain together. The researchers used a heat treatment called annealing to get more crystals to form in the hydrogel.
By increasing the crystal content, the researchers were able to create a gel that was five times more resistant to stress than a freeze-thaw method.
The improved strength of the gel made it possible to secure it to the joint and keep it there.
The ends of bones are covered by a thin layer of cartilage. It hasn't been possible to attach hydrogels to bone or cartilage with enough strength to keep them from falling off. The Duke team came up with a different way of doing things.
They attach the hydrogel to a titanium base using a method called cementing and capping. This is pressed and anchored into a hole. The design stays fastened more firmly when tested.
It is a concern for knee implants to wear over time.
The materials used to make knee implants are stiff and can hurt the other parts of the knee.
In wear tests, artificial and natural cartilage were spun against each other a million times, with a pressure similar to what the knee feels. The scientists found that the surface of their lab-made version held up three times better than the real thing. Because the hydrogel mimics the smooth, slippery, cushiony nature of real cartilage, it protects other joint surfaces from rubbing against the implant.
Cartilage is very long lasting. It can't heal because it doesn't have any blood vessels.
Osteoarthritis is more common in the US than it was a century ago. When conservative treatments don't work, surgery is a possibility. Surgeons have developed a number of minimally-invasive approaches over the years, such as removing loose cartilage or making holes to grow new tissue. Some of the methods fail over time because of the months of rehabilitation required.
Total knee replacement is often considered a last resort. Artificial joints don't last long. There are not very good options for younger patients who want to avoid major surgery for a device that will only need to be replaced again down the line.
The change in treatment for people at this stage will be dramatic.
More information: Jiacheng Zhao et al, A Synthetic Hydrogel Composite with a Strength and Wear Resistance Greater than Cartilage, Advanced Functional Materials (2022). DOI: 10.1002/adfm.202205662 Journal information: Advanced Functional Materials
All Rights Reserved © 2024
