New Flexible & Strong Hydrogel to Replace Conventional Knee Implants
Duke University researchers have created an experimental gel that is the first to match the strength and durability of the thin, slippery layer of cartilage naturally present between the bones in the knee.
The material is incredibly strong and is made up of 60% water, but a single quarter-sized disc of this material can bear the weight of a 100-pound kettlebell without tearing or losing its shape.
The material is incredibly strong and is made up of 60% water, but a single quarter-sized disc of this material can bear the weight of a 100-pound kettlebell without tearing or losing its shape.
New Material to Withstand Heavy Loads
Its developers say it’s the first hydrogel -- materials made of water-absorbing polymers -- capable of withstanding tugging and heavy loads as well as human cartilage, without wearing out over time.
Led by Duke chemistry and materials scientists Ben Wiley and Ken Gall, the research could one day offer people with knee troubles a replacement for damaged cartilage, and an alternative to the 600,000 knee replacement surgeries performed in the U.S. each year.
The new hydrogel consists of two intertwined polymer networks: one made of stretchy spaghetti-like strands and the other more rigid and basketlike, with negative charges along their length. These are reinforced with a third ingredient, a meshwork of cellulose fibers.
When the gel is stretched, the cellulose fibers resist pulling and help hold the material together. And when it is squeezed, the negative charges along the rigid polymer chains repel each other and stick to water, helping it spring back to its original shape.
“Only this combination of all three components is both flexible and stiff and therefore strong,” said co-author Feichen Yang, who earned a chemistry PhD in Wiley’s lab.
When the researchers compared the resulting material to other hydrogels, theirs was the only one that was as strong as cartilage under both squishing and stretching.
Led by Duke chemistry and materials scientists Ben Wiley and Ken Gall, the research could one day offer people with knee troubles a replacement for damaged cartilage, and an alternative to the 600,000 knee replacement surgeries performed in the U.S. each year.
Flexible, Strong and Stiff Material
The new hydrogel consists of two intertwined polymer networks: one made of stretchy spaghetti-like strands and the other more rigid and basketlike, with negative charges along their length. These are reinforced with a third ingredient, a meshwork of cellulose fibers.
When the gel is stretched, the cellulose fibers resist pulling and help hold the material together. And when it is squeezed, the negative charges along the rigid polymer chains repel each other and stick to water, helping it spring back to its original shape.
“Only this combination of all three components is both flexible and stiff and therefore strong,” said co-author Feichen Yang, who earned a chemistry PhD in Wiley’s lab.
When the researchers compared the resulting material to other hydrogels, theirs was the only one that was as strong as cartilage under both squishing and stretching.
In one experiment, the team subjected it to 100,000 cycles of repeat pulling, and the material held up just as well as porous titanium used for bone implants, “which exceeded our initial expectations,” said co-author William Koshut, a PhD student in the Gall lab.
They also rubbed the new material against natural cartilage a million times. They found that its smooth, slippery self-lubricating surface is as wear-resistant as the real thing and four times more wear-resistant than synthetic cartilage implants currently FDA-approved for use in the big toe.
Moving the material from the lab to the clinic would take another three years at least. Initial safety tests suggest the material is nontoxic to lab-grown cells. The next step is to design an implant that they can test in sheep.
The research could offer new options for people with knee pain and get them back to doing the things they love without the long recovery times and limited lifetime associated with cartilage repair or knee replacement surgery.
They also rubbed the new material against natural cartilage a million times. They found that its smooth, slippery self-lubricating surface is as wear-resistant as the real thing and four times more wear-resistant than synthetic cartilage implants currently FDA-approved for use in the big toe.
Moving the material from the lab to the clinic would take another three years at least. Initial safety tests suggest the material is nontoxic to lab-grown cells. The next step is to design an implant that they can test in sheep.
The research could offer new options for people with knee pain and get them back to doing the things they love without the long recovery times and limited lifetime associated with cartilage repair or knee replacement surgery.
Source: Duke University
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