Researchers at University of Limerick have been looking into orthopaedic implants and how to prolong their lifespan. They say their findings could have future applications to help improve patient recovery, as well as decreasing the need for surgical procedures.
The scientists involved in the project were Dr Maurice Collins, Dr Eric Dalton, Barbara Schaller, all of the Stokes Institute at UL; plus Dr JJ Leahy, of the Department of Chemical and Environmental Science at UL.
They said that improving the lifespan of orthopaedic implants would also help lower the risk of infection.
In the US, about 750,000 orthopaedic implant operations are carried out each year, said the scientists at UL today. And by 2030, this figure is expected to increase to 4.5m.
Back in 2009, the US hip and knee market for implants and devices was estimated at US$6.4bn, said Collins, who was the lead researcher on the study. He said that some orthopaedic materials currently have failure rates of 13pc over five years.
“Our research hopes to explain the failure mechanisms in these materials in order to positively impact on the longevity of implants,” said Collins.
Artificial joints, sterilisation methods and wear rates
The UL researchers carried out their research by exploring a link between sterilisation methods and wear in the polyethylene-based material called ultra high molecular weight polyethylene (UHMWPE), which is predominantly used in artificial joints.
They said UHMWPE provides a bearing surface against which hard metal or ceramic components connect. Before surgery, they said these components are sterilised by gamma radiation and this causes complex material interactions that change the mechanical properties of the bearing material, by increasing its stiffness and brittleness.
As a result, Collins said wear rates are also changed by sterilisation processes. He said the subsequent generation of wear debris has been implicated in artificial joint loosening and infection.
The scientists carried out their experimental work using the diamond light source synchrotron.
Said Collins: “The data analysis systems available at that facility allow results to be looked at in new ways, which enables the study of fundamental material properties as a function of sterilisation dosage.”
The next stage of biomedical research
The UL research team is looking to further this work by exploring its translation in further biomedical research, as well as automotive materials and electronics.
They said today that preliminary results from their experiment have now been prepared for publication.
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