title: In situ measurements of local temperature and contact stress magnitude during wear of ceramic-on-ceramic hip joints.
abstract: Fluorescence microprobe spectroscopy was applied to in situ assessments of contact stress and local temperature at the contact point of dry-sliding couples during wear tests of two commercially available ceramic-on-ceramic femoral heads. The investigated ceramic hip implants consisted of either monolithic Al2O3 or Al2O3/ZrO2 composite. A specially designed pin-on-ball tribometer was employed, which enabled directly testing the femoral head components as received from the maker without further manipulation. The strong fluorescence emission from Cr(3+) impurities contained in Al2O3 served as a responsive sensor for both temperature and stress. Analytical corrections for the averaging effects arising from the finite size of the laser probe were made according to a probe response formalism in which geometrical conditions of the sliding couple were incorporated as boundary conditions. The sample-probe interaction at the contact point was then experimentally calibrated by obtaining probe response functions for the two materials investigated. Based on such theoretical and experimental procedures, deconvolutive computational routines could be set up and the true variations of local temperature and stress at the contact point of the bearing surfaces retrieved from the observed time-dependent broadening and shift of a selected spectral band, respectively. The main result of the in situ investigation was that the monolithic sliding couple showed both significantly lower temperature and lower magnitude of compressive stress at the contact point as compared to the composite one, although the composite couple wore at a significantly lower specific wear rate than the monolithic one.
authors: Department of Orthopedic Surgery, Osaka University Medical School, 2-2 Yamadaoka, Suita, 565-0871 Osaka, Japan.
authors: Wenliang
authors: W
authors: Zhu
authors: Ceramic Physics Laboratory and Research Institute for Nanoscience, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto, Japan.
authors: Leonardo
authors: L
authors: Puppulin
authors: Piezotech Japan Ltd., Mukaibata-cho 4, Ichijoji, Sakyo-ku, 606-8326 Kyoto, Japan.
authors: Andrea
authors: A
authors: Leto
authors: Ceramic Physics Laboratory and Research Institute for Nanoscience, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto, Japan.
authors: Yasuhito
authors: Y
authors: Takahashi
authors: Department of Orthopedic Surgery, Osaka University Medical School, 2-2 Yamadaoka, Suita, 565-0871 Osaka, Japan.
authors: Nobuhiko
authors: N
authors: Sugano
authors: Ceramic Physics Laboratory and Research Institute for Nanoscience, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto, Japan; The Center for Advanced Medical Engineering and Informatics, Osaka University, 2-2 Yamadaoka, Suita, 565-0817 Osaka. Electronic address: pezzotti@kit.ac.jp.
authors: Giuseppe
authors: G
authors: Pezzotti
mesh_terms: D002516:Ceramics / Q000032:analysis / Q000737:chemistry*; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation*; D017276:Friction; D006622:Hip Prosthesis; D008365:Manometry / Q000295:instrumentation*; D008422:Materials Testing / Q000295:instrumentation*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D013314:Stress, Mechanical; D013499:Surface Properties; D013817:Thermography / Q000295:instrumentation*
keywords: Ceramic hip joints; Contact stress; Fluorescence spectroscopy; In situ temperature analysis; Tribometer