Effects of the sterilisation method on the wear of UHMWPE acetabular cups tested in a hip joint simulator

S. Affatato, B. Bordini, C. Fagnano, P. Taddei, A. Tinti, A. Toni

Research output: Contribution to journalArticle

Abstract

Ultra-high molecular-weight-polyethylene is the most commonly used bearing material in total joint replacement. Wear of polyethylene is a serious clinical problem that limits the longevity of orthopaedic implants. Information on degradative changes in the material properties and on the methods used for the sterilisation of polyethylene may help in the selection process of orthopaedic implants with the best wear resistance.This study was performed to investigate the effects of the sterilisation method (gamma irradiation and ethylene oxide treatment) on the wear and on the changes in physical properties of polyethylene acetabular cups. At this purpose, gamma-sterilised and ethylene oxide (EtO)-sterilised acetabular cups were tested against CoCr femoral heads in a hip joint simulator run for 5 million cycles in bovine calf serum. The crystallinity of the cups was evaluated by micro-Raman spectroscopy as a function of the inner surface position. The partial least square calibration was used to correlate the Raman spectra with the crystallinity of the polymer measured by differential scanning calorimetry.The analysis performed on soak control acetabular cups demonstrated that the gamma-sterilised cups are significantly more crystalline than the EtO-sterilised ones. The mean crystallinity values obtained for the gamma-sterilised and EtO-sterilised soak control cups were 65.0% and 63.4%, respectively.Weight loss measurements revealed that the gamma-sterilised acetabular cups exhibited a lower wear rate than that by EtO-sterilised. The Raman results obtained on gamma-sterilised and EtO-sterilised acetabular cups showed that the changes in surface crystallinity were mainly caused by irradiation rather than by the mechanical friction during the in vitro tests.

Original languageEnglish
Pages (from-to)1439-1446
Number of pages8
JournalBiomaterials
Volume23
Issue number6
DOIs
Publication statusPublished - Mar 15 2002

Keywords

  • Ethylene oxide gas sterilisation
  • Gamma irradiation
  • In vitro wear
  • Micro-Raman spectroscopy
  • Polyethylene sterilisation

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering

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