Effect of water and serum absorption on wear of unirradiated and crosslinked UHMWPE orthopedic bearing materials

Kathryn Laraia, Nicholas Leone, Rebecca MacDolanald, Thierry A. Blanchet

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

In addition to confounding mass-based wear measurements in serum-lubricated hip simulator experiments, fluid absorption by the acetabular cups may simultaneously modify the wear resistance of the ultra-high molecular weight polyethylene (UHMWPE) from which they are composed. To decouple the fluid absorption and wear processes enabling clearer investigation of this effect, absorption was first imposed during an initial stage where UHMWPE was exposed to pressurized (10 MPa) fluid. This was followed by a second stage, where resultant wear behavior was assessed by a multidirectional pin-on-flat technique that, though still providing a serum-lubricating environment, does not promote the simultaneous fluid absorption occurring in hip simulator testing. Both unirradiated and highly crosslinked UHMWPE were investigated, each with both bovine calf serum and water soaking exposures of duration to 129 days. The pressurized soaking of a highly crosslinked UHMWPE decreased its wear resistance, causing an increase in wear rate by approximately 50% during subsequent serum-lubricated multidirectional pin-on-flat sliding tests as compared to non-soaked material. The magnitude of this effect did not appear to depend on whether the soaking fluid was water or serum, nor did it appear to depend on soak time provided it was at least of a 14-day duration, during which more rapid transient fluid absorption occurs. Such soaking did not produce as pronounced an effect on unirradiated UHMWPE, as its lack of wear resistance likely causes the absorption-affected surface region to be removed within the earliest stages of sliding contact.

Original languageEnglish (US)
Pages (from-to)338-346
Number of pages9
JournalTribology Transactions
Volume49
Issue number3
DOIs
StatePublished - Jul 1 2006

Keywords

  • UHMWPE
  • Unirradiated and crosslinked orthopedic bearing materials
  • Water and serum absorption

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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