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The influence of acetabular cup material on pelvis cortex surface strains, measured using digital image correlation

The influence of acetabular cup material on pelvis cortex surface strains, measured using digital image correlation
The influence of acetabular cup material on pelvis cortex surface strains, measured using digital image correlation
Acetabular cup loosening is a late failure mode of total hip replacements, and peri-prosthetic bone deterioration may promote earlier failure. Preservation of supporting bone quality is a goal for implant design and materials selection, to avoid stress shielding and bone resorption. Advanced polymer composite materials have closer stiffness to bone than metals, ceramics or polymers, and have been hypothesised to promote less adverse bone adaptation. Computer simulations have supported this hypothesis, and the present study aimed to verify this experimentally.

A composite hemi-pelvis was implanted with Cobalt Chromium (CoCr), polyethylene (UHMWPE) and MOTIS®carbon-fibre-reinforced polyether etherketone (CFR-PEEK) acetabular cups. In each case, load was applied to the implanted pelvis and Digital Image Correlation (DIC) was used for surface strain measurement. The test was repeated for an intact hemi-pelvis. Trends in implanted vs. intact bone principal strains were inspected to assess the average principal strain magnitude change, allowing comparison of the potential bone responses to implantation with the three cups.

The CFR-PEEK cup was observed to produce the closest bone strain to the intact hip in the main load path, the superior peri-acetabular cortex (+12% on average, R2=0.84), in comparison to CoCr (+40%, R2=0.91) and UHWMPE cups (?26%, R2=0.94). Clinical observations have indicated that increased periacetabular cortex loading may result in reduced polar cancellous bone loading, leading to longer term losses in periprosthetic bone mineral density. This study provides experimental evidence to verify previous computational studies, indicating that cups produced using materials with stiffness closer to cortical bone recreate physiological cortical bone strains more closely and could, therefore, potentially promote less adverse bone adaptation than stiffer press-fitted implants in current use
0021-9290
719-723
Dickinson, A.S.
10151972-c1b5-4f7d-bc12-6482b5870cad
Taylor, A.C.
39974814-4868-4c73-a3fa-2adfa4be3e46
Browne, M.
6578cc37-7bd6-43b9-ae5c-77ccb7726397
Dickinson, A.S.
10151972-c1b5-4f7d-bc12-6482b5870cad
Taylor, A.C.
39974814-4868-4c73-a3fa-2adfa4be3e46
Browne, M.
6578cc37-7bd6-43b9-ae5c-77ccb7726397

Dickinson, A.S., Taylor, A.C. and Browne, M. (2012) The influence of acetabular cup material on pelvis cortex surface strains, measured using digital image correlation. Journal of Biomechanics, 45 (4), 719-723. (doi:10.1016/j.jbiomech.2011.11.042).

Record type: Article

Abstract

Acetabular cup loosening is a late failure mode of total hip replacements, and peri-prosthetic bone deterioration may promote earlier failure. Preservation of supporting bone quality is a goal for implant design and materials selection, to avoid stress shielding and bone resorption. Advanced polymer composite materials have closer stiffness to bone than metals, ceramics or polymers, and have been hypothesised to promote less adverse bone adaptation. Computer simulations have supported this hypothesis, and the present study aimed to verify this experimentally.

A composite hemi-pelvis was implanted with Cobalt Chromium (CoCr), polyethylene (UHMWPE) and MOTIS®carbon-fibre-reinforced polyether etherketone (CFR-PEEK) acetabular cups. In each case, load was applied to the implanted pelvis and Digital Image Correlation (DIC) was used for surface strain measurement. The test was repeated for an intact hemi-pelvis. Trends in implanted vs. intact bone principal strains were inspected to assess the average principal strain magnitude change, allowing comparison of the potential bone responses to implantation with the three cups.

The CFR-PEEK cup was observed to produce the closest bone strain to the intact hip in the main load path, the superior peri-acetabular cortex (+12% on average, R2=0.84), in comparison to CoCr (+40%, R2=0.91) and UHWMPE cups (?26%, R2=0.94). Clinical observations have indicated that increased periacetabular cortex loading may result in reduced polar cancellous bone loading, leading to longer term losses in periprosthetic bone mineral density. This study provides experimental evidence to verify previous computational studies, indicating that cups produced using materials with stiffness closer to cortical bone recreate physiological cortical bone strains more closely and could, therefore, potentially promote less adverse bone adaptation than stiffer press-fitted implants in current use

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More information

e-pub ahead of print date: 9 January 2012
Published date: 23 February 2012
Organisations: Bioengineering Group

Identifiers

Local EPrints ID: 207935
URI: https://eprints.soton.ac.uk/id/eprint/207935
ISSN: 0021-9290
PURE UUID: cb249af5-63fc-4ca5-9b06-e6164b99fcf2
ORCID for A.S. Dickinson: ORCID iD orcid.org/0000-0002-9647-1944
ORCID for M. Browne: ORCID iD orcid.org/0000-0001-5184-050X

Catalogue record

Date deposited: 13 Jan 2012 15:16
Last modified: 31 Jul 2019 00:50

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