Failure mechanism of the all-polyethylene glenoid implant

Sarah Junaid, Sanjay Gupta, Sanjay Sanghavi, Carolyn Anglin, Roger Emery, Andrew Amis, Ulrich Hansen

Research output: Contribution to journalArticlepeer-review


Fixation failure of glenoid components is the main cause of unsuccessful total shoulder arthroplasties. The characteristics of these failures are still not well understood, hence, attempts at improving the implant fixation are somewhat blind and the failure rate remains high. This lack of understanding is largely due to the fundamental problem that direct observations of failure are impossible as the fixation is inherently embedded within the bone. Twenty custom made implants, reflecting various common fixation designs, and a specimen set-up was prepared to enable direct observation of failure when the specimens were exposed to cyclic superior loads during laboratory experiments. Finite element analyses of the laboratory tests were also carried out to explain the observed failure scenarios. All implants, irrespective of the particular fixation design, failed at the implant-cement interface and failure initiated at the inferior part of the component fixation. Finite element analyses indicated that this failure scenario was caused by a weak and brittle implant-cement interface and tensile stresses in the inferior region possibly worsened by a stress raiser effect at the inferior rim. The results of this study indicate that glenoid failure can be delayed or prevented by improving the implant/cement interface strength. Also any design features that reduce the geometrical stress raiser and the inferior tensile stresses in general should delay implant loosening.

Original languageEnglish
Pages (from-to)714-719
Number of pages6
JournalJournal of Biomechanics
Issue number4
Early online date24 Nov 2009
Publication statusPublished - 3 Mar 2010

Bibliographical note

© 2009 Elsevier Ltd. open access under CC BY-NC-ND license.


  • equipment failure analysis
  • shoulder joint
  • joint Instability
  • joint Prosthesis
  • polyethylene
  • prosthesis failure


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