Mathys Orthopaedie GmbH

Neustadt an der Weinstraße, Germany

Mathys Orthopaedie GmbH

Neustadt an der Weinstraße, Germany
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Gremillard L.,CNRS Laboratory for Materials: Engineering and Science | Wei C.,CNRS Laboratory for Materials: Engineering and Science | Chevalier J.,CNRS Laboratory for Materials: Engineering and Science | Hans K.,Mathys Orthopaedie GmbH | Oberbach T.,Mathys Orthopaedie GmbH
Journal of the European Ceramic Society | Year: 2017

Hydrothermal ageing is one lifetime-limiting phenomenon of zirconia-based ceramics and composites for many applications, from biomedical implants to ferrules and watches. Predicting hydrothermal ageing at use-temperature implies a set of accelerated ageing experiments conducted under water vapour at several, high temperatures (usually between 100. °C and 140. °C). From these data, the activation energy of ageing can be determined, and thus ageing can be predicted at any temperature. However, obtaining precise extrapolations with this procedure requires the use of lower temperatures (70 or 80. °C), leading to a rather long procedure (up to a few thousand hours), and should involve at least one specimen for each test temperature. This article presents a new procedure that allows the determination of all ageing parameters and the estimation of kinetics at use-temperatures with the use of a single specimen within a shorter time, accurate enough for fast screening of new materials. © 2017 Elsevier Ltd.


Wuttke V.,Mathys Orthopaedie GmbH | Witte H.,TU Ilmenau | Kempf K.,Mathys Orthopaedie GmbH | Oberbach T.,Mathys Orthopaedie GmbH | Delfosse D.,Mathys Ltd. Bettlach
Biomedizinische Technik | Year: 2011

Ceramic-on-ceramic articulations are a frequently used bearing for total hip replacements. This success mainly is due to their excellent tribological properties. Ceramics can withstand high pressure loads due to its brittleness but only low bending stresses. A ceramic ball head fracture is the result of subcritical crack growth. This kind of fracture in vivo can abet by damage or contamination of the stem cone. The main goal of this work is to provide a risk assessment of different possible damage mechanisms and contaminations that may result in lower fracture strength of a ceramic ball head. To simulate potential causes, different types and dimensions of metal wire, foils, hair, and lubricants were inserted between the ceramic ball head and the metal cone of the stem. The test results clearly show that fracture strength is negatively influenced by most of the inhomogeneities between the cone and the head because they increase the peak stresses acting on a part of the ceramic ball head. The results of this article clearly confirm the demand for an undamaged taper fit "free of contamination" between the ceramic head and the metal cone during implantation. © 2011 by Walter de Gruyter Berlin Boston 2011.


Ortmann C.,Mathys Orthopaedie GmbH | Oberbach T.,Mathys Orthopaedie GmbH | Richter H.,Fraunhofer Institute for Ceramic Technologies and Systems | Puhlfurss P.,Fraunhofer Institute for Ceramic Technologies and Systems
Journal of the European Ceramic Society | Year: 2012

Properties and proof of suitability of homogeneously and graded ZTA bioceramics with various Y 2O 3 stabilized zirconia contents were investigated. Therefore porous alumina was infiltrated with different amounts of Y 2O 3 doped ZrO 2 precursors. At homogeneously infiltrated samples biaxial flexural strength and wear behavior were investigated (ISO 6474). Subsequently, at hip joint heads the static fracture strength was determined (ISO 7206-10). Materials ranging from approx. 4 to 20wt% Y 2O 3 stabilized zirconia were characterized relative to the sinter density, the microstructure, the phase composition and the dispersion of the stabilized zirconia phase. Bioceramics showed high sinter density, fine microstructures, excellent wear property and significantly increased biaxial flexural strength. A 41% increase in strength through the formation of Y 2O 3 stabilized zirconia gradient in the conical bore of the heads was reached. Low compressive stresses in cone of this heads were found. ZTA bioceramics are potentially suitable for use as hip replacement components. © 2011 Elsevier Ltd.

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