title: Accelerating aging of zirconia femoral head implants: change of surface structure and mechanical properties.
abstract: Recently, alternations of zirconia ceramic femoral heads of total hip prostheses during in vivo conditions have caused concern in the medical disciplines regarding phase transformation of zirconia prosthetic components. In this paper, we have investigated the mechanical and structural properties of different laboratory aged zirconia femoral heads and correlated changes in mechanical properties with the phase compositions of the sample. From laser microscope observation, cross-sectional Scanning electron microscopy imaging, and X-ray diffraction analysis on the surface of the zirconia femoral heads, we found monoclinic to tetragonal phase transformation in zirconia prostheses over time during the aging process in the laboratory. Mechanical properties, mainly hardness (H) and Young's modulus (E) values, were measured by nanoindentation technique on the surface of these implants. The results showed that both H and E values decreased with increased monoclinic phase in zirconia, thus confirming a phase transformation over time during aging.
authors.affiliation: Department of Physics University of Alabama at Birmingham, Birmingham, Alabama 35294-1170, USA. shafiul@uab.edu
authors.forename: S
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Yogesh K
authors.initials: YK
authors.lastname: Vohra
authors.forename: Jack E
authors.initials: JE
authors.lastname: Lemons
authors.forename: Masaru
authors.initials: M
authors.lastname: Ueno
authors.forename: Junji
authors.initials: J
authors.lastname: Ikeda
mesh_terms: D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D002516:Ceramics; D006622:Hip Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011475:Prosthesis Failure; D013499:Surface Properties; D014961:X-Ray Diffraction; D015040:Zirconium
chemical_list: D001672:Biocompatible Materials; D015040:Zirconium; C028541:zirconium oxide