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A large taper mismatch is one of the key factors behind high wear rates and failure at the taper junction of total hip replacements: A finite element wear analysis.

Ashkanfar, A and Langton, DJ and Joyce, TJ (2017) A large taper mismatch is one of the key factors behind high wear rates and failure at the taper junction of total hip replacements: A finite element wear analysis. JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, 69. pp. 257-266. ISSN 1751-6161

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Abstract

Total hip replacement (THR) is one of the most successful orthopaedic surgeries; however, failures can occur due to adverse reactions to wear debris. Recently, a large number of failures linked to the release of metal particles from the taper junction between femoral head and femoral stem have been reported. One possible reason for this may be design variations such as taper mismatches associated with the taper and trunnion angles. Could a large taper mismatch lead to inappropriate contact mechanics and increase relative micromotion and thus wear? In this study, 3D finite element (FE) models of a commercial THR from a perfectly matched interface to large taper mismatches and a wear algorithm were used to investigate the extent of wear that could occur at this junction and identify the optimum tolerances in order to reduce the wear. A co-ordinate measuring machine (CMM) was used to analyse the wear depth and volumetric wear rate of the tapers of 54 explanted 36mm diameter Cobalt Chromium femoral heads, which had been in service for 5.1 years in average, to validate the FE analyses. It was found that a large taper mismatch (e.g. 9.12´) results in a high wear rate (2.960mm(3) per million load cycles). Such wear rates can have a major negative effect on the clinical outcomes of these implants. It was also found that even a slight reduction in mismatch significantly reduced the magnitude of the wear rates (0.069mm(3) per million load cycles on average for 6´ taper mismatch). It is recommended that the cone angles of femoral head and femoral trunnion should be manufactured to produce a taper mismatch of less than 6´ at the taper junction.

Item Type: Article
Uncontrolled Keywords: 0903 Biomedical Engineering, 0912 Materials Engineering, 0913 Mechanical Engineering
Subjects: R Medicine > R Medicine (General)
T Technology > TJ Mechanical engineering and machinery
Divisions: Maritime and Mechanical Engineering
Publisher: ELSEVIER SCIENCE BV
Related URLs:
Date Deposited: 06 Feb 2017 11:49
Last Modified: 07 Sep 2017 12:56
DOI or Identification number: 10.1016/j.jmbbm.2017.01.018
URI: http://researchonline.ljmu.ac.uk/id/eprint/5442

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