Credit: F. Jacquot; Wikipedia.
Although they are somewhat light on the details, researchers at the Changzhou Institute of Light Industry Technology (CIT) say they may have found a way to address fatigue problems associated with two materials of interest for use as cartilage-like coating material for joint prostheses.
Led by Maoquan Xue, the CIT group wanted to see if they could improve the performance of UHMWPE (ultra-high-molecular-weight polyethylene) and PEEK (polyether ether ketone) that had an unfortunate knack of developing fatigue cracks. Presumably, that occurs because the long polymer chains carry the force from one point to the next.
They began by modifying UHMWPE and PEEK “cartilage” by adding unspecified ceramic particles and fibers, which alone, they say, improved the spatial structure of the material—but not enough to eliminate all fatigue wear. They hit on well-performing cartilage when they doused the mix with a gamma radiation burst. They says this irradiated combination breaks the main polymer chains without disrupting the overall structure of the artificial cartilage. The free radicals are recrosslinked, improving the mechanical properties and tribological properties of the materials.
According to a news release, the group believes the irradiated cartilage composite “could toughen up plastic joints in joint replacement surgeries and make them strong enough to last for years.”
The release continues, “As a result of the gamma burst, there is no way for microscopic fractures to be propagated throughout the material because there are no long stretches of polymer.”
Xue and others in the group say the composite has a leg up on alternative artificial joint coatings, such as nylon and nonstick polymers, because the latter produce debris that ultimately causes inflammation and pain. They also believe the composite is more “biocompatible” and may be a good host for the of addition of bone-generating cells.
The work was published in a paper in the International Journal of Biomedical Engineering and Technology (doi:0.1504/IJBET.2011.042495).