Do total hip arthroplasty polyethylene liners without free radicals oxidize in vivo or ex vivo?

J Biomed Mater Res B Appl Biomater. 2022 May;110(5):1113-1119. doi: 10.1002/jbm.b.34985. Epub 2021 Dec 11.


Crosslinking substantially reduces the wear of ultra-high molecular weight polyethylene (UHMWPE) used in total hip arthroplasty (THA) but some reports have indicated that first generation liners manufactured without antioxidants may be vulnerable to in vivo oxidation. This study evaluated maximum oxidation using Fourier transform infrared spectroscopy per ASTM F2102-06ε1 and linear head penetration using a coordinate measuring machine among 66 revision-retrieved THA components with in vivo durations ranging from 0.02 to 24.6 years. These included 30 liners crosslinked with 5 Mrad of gamma radiation and then melted, 13 non-crosslinked, never-irradiated liners sterilized with gas plasma and 23 non-crosslinked, never-irradiated liners sterilized with ethylene oxide. All liners were vacuum-sealed and stored at -20°C prior to analysis with the exception of three retrievals of each material type that were stored in air for 9.9 to 21.5 years. All 57 vacuum-sealed and frozen retrievals demonstrated good oxidative stability with maximum oxidation indices (OIs) less than 1.0 and 75% (43/57) of these liners had maximum OIs less than 0.1. Linear penetration measurements were lower in the crosslinked liners compared to non-crosslinked retrievals. Although instances of oxidation and embrittlement were found after ex vivo storage in air among liners that did not have free radicals at the time of implantation, in vivo oxidation does not appear to be a clinical concern through the first decade of service for crosslinked liners and at up to 25 years after surgery for non-crosslinked liners.

Keywords: hip arthroplasty; in vivo oxidation; irradiated and melted crosslinking; non-irradiated polyethylene; revision retrieved liners.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arthroplasty, Replacement, Hip*
  • Free Radicals
  • Hip Prosthesis*
  • Humans
  • Polyethylene / chemistry
  • Polyethylenes / chemistry
  • Prosthesis Design
  • Prosthesis Failure
  • Reoperation


  • Free Radicals
  • Polyethylenes
  • Polyethylene