Chemically driven tetragonal-to-monoclinic polymorphic transformation in retrieved ZTA femoral heads from dual mobility hip implants
Chemically driven tetragonal-to-monoclinic polymorphic transformation in retrieved ZTA femoral heads from dual mobility hip implants
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DOI：
10.1016/j.jmbbm.2015.11.032
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发表时间：
2016-03-01
影响因子：
3.9
通讯作者：
Pezzotti, G.
中科院分区：
文献类型：
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作者：
Boffelli, M.;Doimo, A.;Pezzotti, G.
通过共焦拉曼光谱法研究了两个短期（两个月和九个月）回收的氧化锆增韧氧化铝（ZTA）股骨头和来自同一制造商的九个原始股骨头的表面稳定性。定量估计的单斜相体积分数已进行了非磨损和主要磨损区的检索头，不变地显示高体积分数的单斜多晶型。使用共焦配置的拉曼探针在主要磨损区非破坏性收集的深度（亚表面）剖面确实证实了多晶型转变向下延伸至股骨头支承表面以下100 μ m。四方晶向单斜晶转变速率的加速导致在非常短期的体内暴露内意外地高分数的单斜晶相。体内相变比根据简单模拟体外热液环境实际预测的要显著得多，并且不能简单地归因于轴承表面正常使用期间产生的机械应力场。相反，ZTA股骨头表面上金属污染的化学后果被证明在相不稳定中起着最有害的作用。(C)2015爱思唯尔有限公司版权所有。
Two short-term (two and nine months) retrieved zirconia-toughened alumina (ZTA) femoral heads and nine pristine femoral heads from the same manufacturer have been investigated with respect to their surface stability by means of confocal Raman spectroscopy. Quantitative estimations of monoclinic volume fraction have been carried out in both non-wear and main wear zones of the retrieved heads, which invariantly showed high volume fractions of monoclinic polymorph. In-depth (sub-surface) profiles, non-destructively collected in the main wear zones with the Raman probe in confocal configuration, indeed confirmed that polymorphic transformation was extended down to 100 mu m below the bearing surface of the femoral heads. Acceleration of tetragonal-to-monoclinic transformation rate leads to unexpectedly high fractions of monoclinic phase within very short-term in-vivo exposures. Phase transformation in-vivo is much more marked than what one could actually predict according to simply simulating a hydrothermal environment in-vitro and could not be simply ascribed to the mechanical stress fields generated during normal service at the bearing surface. Instead, the chemical consequences of metal contamination on the ZTA femoral head surface are shown to play the most detrimental role in phase destabilization. (C) 2015 Elsevier Ltd. All rights reserved.