Wear in the prosthetic shoulder: association with design parameters


Hopkins, Andrew R., Hansen, Ulrich N., Amis, Andrew A., Knight, Lucy, Taylor, Mark, Levy, Ofer and Copeland, Stephen A. (2007) Wear in the prosthetic shoulder: association with design parameters. Journal of Biomechanical Engineering, 129, (2), 223-230. (doi:10.1115/1.2486060).

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Original Publication URL: http://dx.doi.org/10.1115/1.2486060

Description/Abstract

Total replacement of the glenohumeral joint provides an effective means for treating a
variety of pathologies of the shoulder. However, several studies indicate that the procedure
has not yet been entirely optimized. Loosening of the glenoid component remains the
most likely cause of implant failure, and generally this is believed to stem from either
mechanical failure of the fixation in response to high tensile stresses, or through osteolysis
of the surrounding bone stock in response to particulate wear debris. Many computational
studies have considered the potential for the former, although only few have
attempted to tackle the latter. Using finite-element analysis an investigation, taking into
account contact pressures as well as glenohumeral kinematics, has thus been conducted,
to assess the potential for polyethylene wear within the artificial shoulder. The relationships
between three different aspects of glenohumeral design and the potential for wear
have been considered, these being conformity, polyethylene thickness, and fixation type.
The results of the current study indicate that the use of conforming designs are likely to
produce slightly elevated amounts of wear debris particles when compared with less
conforming joints, but that the latter would be more likely to cause material failure of the
polyethylene. The volume of wear debris predicted was highly influenced by the rate of
loading, however qualitatively it was found that wear predictions were not influenced by
the use of different polyethylene thicknesses nor fixation type while the depth of wearing
was. With the thinnest polyethylene designs 2 mm the maximum depth of the wear scar
was seen to be upwards of 20% higher with a metal-backed fixation as opposed to a
cemented design. In all-polyethylene designs peak polymethyl methacrylate tensile
stresses were seen to reduce with increasing polyethylene thickness. Irrespective of the
rate of loading of the shoulder joint, the current study indicates that it is possible to
optimize glenoid component design against abrasive wear through the use of high conformity
designs, possessing a polyethylene thickness of at least 6 mm.

Item Type: Article
ISSNs: 0148-0731 (print)
Related URLs:
Keywords: shoulder, finite elements, wear, orthopaedics
Subjects: T Technology > TJ Mechanical engineering and machinery
R Medicine > RD Surgery
Divisions: University Structure - Pre August 2011 > School of Engineering Sciences > Bioengineering Sciences
ePrint ID: 47592
Date Deposited: 03 Aug 2007
Last Modified: 27 Mar 2014 18:31
URI: http://eprints.soton.ac.uk/id/eprint/47592

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