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Sunday, 02/03/2019 5:00:52 PM

Sunday, February 03, 2019 5:00:52 PM

Post# of 40710
Characterisation and Biological Impact of Wear Particles from Composite Ceramic Hip Replacements

Both the model and clinically-relevant BIOLOX® Delta ceramic wear particles demonstrated significant reduction in the viability of L929 fibroblast cells at very high doses (500µm3?of particles per cell), however no cytotoxic effects were observed at the lower clinically-relevant doses (0.5-0.05µm3?per cell). The BIOLOX® Delta ZTA ceramic model particles failed to stimulate an inflammatory response in terms of TNF-a release and did not cause any significant DNA damage or production of reactive oxygen species (oxidative stress) in PBMNCs from all donors. However, high doses (50µm3 per cell) of clinically-relevant BIOLOX® Delta ZTA ceramic wear particles caused significantly elevated levels of TNF-a release from PBMNCs. But, there were no significant effects in terms of DNA damage and oxidative stress in PBMNCs from all donors. This study demonstrated that there was a threshold volume of clinically-relevant ceramic wear particles required to stimulate significant TNF-a release from PBMNCs. However, these doses were not clinically-relevant and highly unlikely to occur in vivo due to the extremely low wear rates of CoC bearings. This comprehensive study indicated that composite ZTA Delta ceramic hip replacements had a low biological impact, which may enhance long-term clinical performance. The results from this study are only relevant for BIOLOX® Delta ZTA ceramics and not other manufacturers ceramics.



http://etheses.whiterose.ac.uk/20563/

This article shows that there is a cytotoxic effect at high doses but states that these doses are not clinically relavant based on current in-vitro models. However recent articles showing ZTA phase instability in the presence of metal particulates and softening due to chemomechanical effects show a significant deviation of wear particle release between In-vitro & In-vivo models. This deviation is confirmed by Bertrand et al:

corroborate the previous findings that ceramic-on-ceramic periprosthetic revision tissue is fibrous and offer an explanation for this observation. We detected a long-term inflammatory response of PBMCs and an inflammatory response of fibroblasts to ATZ and ZTA ceramic. These findings partially explain the fibrotic tissue change in periprosthetic tissue of ceramic-on-ceramic bearings.



The author argument that significant levels of TNF-a release from PBMCs in wear thresholds 50µm3 per cell and higher is not clinically relevant based on in-vitro models is clearly off based compared to real world observations! Clearly in-vitro models fail to account for biological influences found in-vivo. To state something isn't relevant based on flawed modeling is very deceptive especially since future research is often built off these flawed studies.
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