title: A testing protocol combining shocks, hydrothermal ageing and friction, applied to Zirconia Toughened Alumina (ZTA) hip implants.
abstract: Ceramics are materials of choice for hip joint implants because of their excellent biocompatibility and mechanical properties. Wear of the bearing couple (femoral head and cup) remains one of the main concerns of hip implants. Although ceramics are known for their good tribological properties, shocks due to micro-separation, friction and hydrothermal ageing in physiological environment remain the three main sources of wear. It has been recently suggested that shock effects dominate but the three degradation mechanisms were so far simulated separately. We developed a procedure that combines sequences of shocks, hydrothermal ageing in an autoclave and friction on hip-walking simulator to investigate their combined effects on Zirconia Toughened Alumina (ZTA) implants. Our results confirm that shocks can be considered as the key phenomenon causing wear, and that their effect is independent of friction and hydrothermal degradation. The analysis of retrieved femoral heads reveals wear features comparable to the ones created experimentally by shocks. Standards (ASTM or ISO) could be improved by including shock tests, which are more relevant than wear tests currently performed on hip simulators at least for Ceramic-on- Ceramic couplings.
authors.affiliation: Ecole Nationale Supérieure des Mines de Saint-Etienne, CIS-EMSE, SAINBIOSE, INSERM U1059, F-42023 Saint-Etienne, France; Université de Lyon, F-69000 Lyon, France. Electronic address: armelle.perrichon@emse.fr.
authors.forename: Armelle
authors.initials: A
authors.lastname: Perrichon
authors.affiliation: Laboratoire de Géologie de Lyon, Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Reynard
authors.affiliation: Université de Lyon, INSA-Lyon, MATEIS, UMR CNRS 5510, 20 Avenue Einstein, 69621 Villeurbanne, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Gremillard
authors.affiliation: Université de Lyon, INSA-Lyon, MATEIS, UMR CNRS 5510, 20 Avenue Einstein, 69621 Villeurbanne, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Chevalier
authors.affiliation: Chirurgie Orthopédique et Traumatologie, CHU Saint-Etienne, Avenue Albert Raimond, 42270 Saint-Priest-en-Jarez, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Farizon
authors.affiliation: Ecole Nationale Supérieure des Mines de Saint-Etienne, CIS-EMSE, SAINBIOSE, INSERM U1059, F-42023 Saint-Etienne, France; Université de Lyon, F-69000 Lyon, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Geringer
mesh_terms: D000537:Aluminum Oxide / Q000032:analysis*; D002516:Ceramics; D017276:Friction; D006622:Hip Prosthesis; D008422:Materials Testing; D011475:Prosthesis Failure; D013499:Surface Properties; D015040:Zirconium / Q000032:analysis*
chemical_list: D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide
keywords: Ceramics; Explants; Hip implants; Shocks; Wear; Zirconia phase transformation