In vitro versus in vivo phase instability of zirconia-toughened alumina femoral heads: A critical comparative assessment

Giuseppe Pezzotti, Saverio Affatato, Alfredo Rondinella, Makiko Yorifuji, Elia Marin, Wenliang Zhu, Bryan J. McEntire, B. Sonny Bal, Kengo Yamamoto

Research output: Contribution to journalArticlepeer-review

Abstract

A clear discrepancy between predicted in vitro and actual in vivo surface phase stability of BIOLOX®delta zirconia-toughened alumina (ZTA) femoral heads has been demonstrated by several independent research groups. Data from retrievals challenge the validity of the standard method currently utilized in evaluating surface stability and raise a series of important questions: (1) Why do in vitro hydrothermal aging treatments conspicuously fail to model actual results from the in vivo environment? (2) What is the preponderant microscopic phenomenon triggering the accelerated transformation in vivo? (3) Ultimately, what revisions of the current in vitro standard are needed in order to obtain consistent predictions of ZTA transformation kinetics in vivo? Reported in this paper is a new in toto method for visualizing the surface stability of femoral heads. It is based on CAD-assisted Raman spectroscopy to quantitatively assess the phase transformation observed in ZTA retrievals. Using a series of independent analytical probes, an evaluation of the microscopic mechanisms responsible for the polymorphic transformation is also provided. An outline is given of the possible ways in which the current hydrothermal simulation standard for artificial joints can be improved in an attempt to reduce the gap between in vitro simulation and reality.

Original languageEnglish
Article number466
Pages (from-to)1-23
Number of pages23
JournalMaterials
Volume10
Issue number5
DOIs
Publication statusPublished - 2017

Keywords

  • Femoral head
  • Hydrothermal aging
  • In vitro
  • In vivo
  • Raman spectroscopy
  • ZTA

ASJC Scopus subject areas

  • Materials Science(all)

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