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G. Reinisch, R. Markut, S. Seidler:
"Tribological Aspects and Nanoindentation Measurements of the "Viennese Cross-Linked Hip Retrievals"";
in: "COST 533 biotribology - Materials for improved wear resistance of total artificial joints", issued by: Tekniker research alliance; Tekniker - research alliance, 2007, ISBN: 978-84-932064-4-4, 13 - 25.

Two retrieved, one in-vitro tested and one shelf aged highly cross-linked UHMWPE (X-PE) liner were characterised on their tribological and micro-mechanical properties. The maximum linear penetration of one explanted liner is 65 µm corresponding to 1.5 mm³ volumetric devia-tion after 2 years in-vivo. Due to severe deformation of the second retrieval no penetration could be assessed. For the in-vitro tested X-PE cup a volumetric wear rate of 2.58 mm³/106 cycles was measured. Abrasive wear traces dominate the tribological impression. One re-trieval, the in-vitro tested and the shelf aged X-PE cup were characterised by micromechani-cal properties. The minimum indentation hardness- and minimum indentation modulus values of all three specimen are at the same level, 0.03 GPa and 0.5 GPa respectively. As a reference conventional unsterilised and sterilised (2.5 Mrad gamma-radiation) UHMWPE was assessed. The level of the hardness and indentation modulus is higher in the tested unsterilised conven-tional UHMWPE. The highest values are measured in sterilised conventional UHMWPE. A depth profile of the indentation hardness and indentation moduls perpendicular to the worn surface exhibits a maximum of the two properties at approx. 2000 µm below the worn sur-face. The depth profile of the shelf aged liner showed as slight decrease of the indentation modulus facing to the implant backside, whereas the hardness showed no decrease. For the retrieved component the tested micro-mechanical properties remained nearly constant throughout the thickness of the liner.

PE-UHMW, Hip joint replacement, Tribology, Nanoindentation