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Wear
and debris generation of Ultrahigh molecular weight polyethylene in total artificial
joints |
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that can occur during the
walking cycle. The PEDEBA tribometer was |
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developed to allow, for
the first time, visualisation of the contact and |
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wear processes in knee
prostheses under different tribological |
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conditions of sliding,
rolling and combined rolling and sliding. Oxidative |
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degradation of the UHMWPE
was found to increase the wear of |
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UHMWPE as was damage to
the femoral counterface. The total |
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number of wear particles
at failure was quantified for the first time. In |
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order to enable realistic
in vitro cell culture studies to be undertaken, |
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sterile endotoxin free
wear tests were developed to generate |
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physiologically relevant
wear debris. These studies have been carried |
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out with micron and
submicron size polyethylene particles and for the |
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first time with real
UHMWPE wear debris. Cell culture models have |
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been successfully
developed, to assess the inflammatory response, |
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the immune response, bond
resorption potential and bone growth |
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potential, both in the
presence and absence of the UHMWPE wear |
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particles. It was found
that debris caused an inhibiting effect on |
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osteoblast growth and
inhibition of osteoclast cell growth and function. |
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Many aspects of the
application of this focused fundamental research |
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project and the
exploitation of the research methods in new applied |
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research and development
projects are underway. |
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These developments and
projects include studies of alternative and modified polyethylenes for hip prostheses,
metal on metal, metal on ceramic and ceramic on ceramic bearings for hip prostheses and
surface engineered hip prostheses. Further work is being carried out in the development of
standard accelerated test methodologies for hip prostheses, the develoment and evaluation
of knee jont simulators and the development of in vitro tissue equivalent cell culture
models for predictions of functional compatibility. These new projects and developments
have involved 20 different industrial partners and the value of the externally funded work
is in excess of 3 M ECUs. |
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