Determination of crystallinity and crystal structure of hylamer™ polyethylene after in vivo wear

M. Visentin, S. Stea, M. De Clerico, M. Reggiani, C. Fagnano, S. Squarzoni, A. Toni

Research output: Contribution to journalArticle

Abstract

Hylamer™ polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer™ components used in joint prostheses, if sterilized by gamma rays in the presence of oxygen, are easily affected by wear, which leads to osteolysis. The authors have analyzed the crystallinity of polyethylene liners removed from seven patients who had received Hylamer™ polyethylene implants sterilized by gamma rays in air and had suffered prosthetic loosening, using Raman spectroscopy coupled with partial least squares (PLS) analysis. The results have been compared to those of two controls who had received Hylamer™ polyethylene implants sterilized by gamma irradiation in a nitrogen atmosphere. The crystal structure of wear particles released into the tissues from the Hylamer™ liners sterilized by gamma rays in air is also studied. The materials undergoing two different types of sterilization methods show different crystallinity values (71.50 vs. 69.43), but the crystallinity do not change according to wear (worn and unworn liner region). Both monoclinic and orthorhombic phases are present in the liner, while in wear debris prevalently monoclinic crystals are found in both types of sterilized liners. Different crystallinity rates can explain different wear rates observed in vivo.

Original languageEnglish
Pages (from-to)131-145
Number of pages15
JournalJournal of Biomaterials Applications
Volume21
Issue number2
DOIs
Publication statusPublished - Oct 2006

Keywords

  • Crystallinity
  • Hylamer™
  • Polyethylene
  • Raman spectroscopy
  • Wear

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials

Fingerprint Dive into the research topics of 'Determination of crystallinity and crystal structure of hylamer™ polyethylene after in vivo wear'. Together they form a unique fingerprint.

  • Cite this