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Inter-subject variability effects on the primary stability of a short cementless femoral stem

Inter-subject variability effects on the primary stability of a short cementless femoral stem
Inter-subject variability effects on the primary stability of a short cementless femoral stem
This paper is concerned with the primary stability of the Furlong Evolution® cementless short stem across a spectrum of patient morphology. A computational tool is developed that automatically selects and positions the most suitable stem from an implant system made of a total of 48 collarless stems to best match a 3D model based on a library of CT femur scans (75males and 34 females). Finite Element contact models of reconstructed hips, subjected to physiologically-based boundary constraints and peak loads of walking mode, were simulated using a coefficient of friction of 0.4 and an interference-fit of 50 ?m. Maximum and average implant micromotions across the subpopulation were predicted to be 100±7 ?m and 7±5 ?m with ranges [15 ?m, 350 ?m] and [1 ?m, 25 ?m], respectively. The computed percentage of implant area with micromotions greater than reported critical values of 50 ?m, 100 ?m and 150 ?m never exceeded 14%, 8% and 7%, respectively. To explore the possible correlations between anatomy and implant performance, response surface models for micromotion metrics were constructed. Detailed morphological analyses were conducted and a clear nonlinear decreasing trend was observed between implant average micromotion and both the metaphyseal canal flare indices and average densities in Gruen zones The present study demonstrates that the primary stability and tolerance of the short stem to variability in patient anatomy were high, reducing the need for patient stratification. In addition, the developed tool could be utilised to support implant design and planning of femoral reconstructive surgery.
short stem, primary stability, inter-subject variability
0021-9290
1032-1042
Bah, M.T.
b5cd0f47-016f-485c-8293-5f6bf8a7ef1a
Shi, Junfen
ccf07607-3ee9-4c29-b326-4f9685fa1a6e
Heller, Markus O.
3da19d2a-f34d-4ff1-8a34-9b5a7e695829
Suchier, Yanneck
862eb630-1f4f-4a9e-a6cf-d940e900e94b
Lefebvre, Fabien
0b1b7c88-54d7-4c65-8d39-0c567f8928f3
Young, Philippe
251d84a2-cb36-4271-8d0a-2d6fcfa58c0f
King, Leonard
7442bd3c-ed4c-46aa-9d9b-1898a113c740
Dunlop, Douglas G.
5f8d8b5c-e516-48b8-831f-c6e5529a52cc
Boettcher, Mick
50e8e36f-d005-4a80-8faa-65ccb3d2063c
Draper, Edward
5acf55af-6608-4cc4-aa42-ace32e24c399
Browne, Martin
6578cc37-7bd6-43b9-ae5c-77ccb7726397
Bah, M.T.
b5cd0f47-016f-485c-8293-5f6bf8a7ef1a
Shi, Junfen
ccf07607-3ee9-4c29-b326-4f9685fa1a6e
Heller, Markus O.
3da19d2a-f34d-4ff1-8a34-9b5a7e695829
Suchier, Yanneck
862eb630-1f4f-4a9e-a6cf-d940e900e94b
Lefebvre, Fabien
0b1b7c88-54d7-4c65-8d39-0c567f8928f3
Young, Philippe
251d84a2-cb36-4271-8d0a-2d6fcfa58c0f
King, Leonard
7442bd3c-ed4c-46aa-9d9b-1898a113c740
Dunlop, Douglas G.
5f8d8b5c-e516-48b8-831f-c6e5529a52cc
Boettcher, Mick
50e8e36f-d005-4a80-8faa-65ccb3d2063c
Draper, Edward
5acf55af-6608-4cc4-aa42-ace32e24c399
Browne, Martin
6578cc37-7bd6-43b9-ae5c-77ccb7726397

Bah, M.T., Shi, Junfen, Heller, Markus O., Suchier, Yanneck, Lefebvre, Fabien, Young, Philippe, King, Leonard, Dunlop, Douglas G., Boettcher, Mick, Draper, Edward and Browne, Martin (2015) Inter-subject variability effects on the primary stability of a short cementless femoral stem. Journal of Biomechanics, 48 (6), 1032-1042. (doi:10.1016/j.jbiomech.2015.01.037).

Record type: Article

Abstract

This paper is concerned with the primary stability of the Furlong Evolution® cementless short stem across a spectrum of patient morphology. A computational tool is developed that automatically selects and positions the most suitable stem from an implant system made of a total of 48 collarless stems to best match a 3D model based on a library of CT femur scans (75males and 34 females). Finite Element contact models of reconstructed hips, subjected to physiologically-based boundary constraints and peak loads of walking mode, were simulated using a coefficient of friction of 0.4 and an interference-fit of 50 ?m. Maximum and average implant micromotions across the subpopulation were predicted to be 100±7 ?m and 7±5 ?m with ranges [15 ?m, 350 ?m] and [1 ?m, 25 ?m], respectively. The computed percentage of implant area with micromotions greater than reported critical values of 50 ?m, 100 ?m and 150 ?m never exceeded 14%, 8% and 7%, respectively. To explore the possible correlations between anatomy and implant performance, response surface models for micromotion metrics were constructed. Detailed morphological analyses were conducted and a clear nonlinear decreasing trend was observed between implant average micromotion and both the metaphyseal canal flare indices and average densities in Gruen zones The present study demonstrates that the primary stability and tolerance of the short stem to variability in patient anatomy were high, reducing the need for patient stratification. In addition, the developed tool could be utilised to support implant design and planning of femoral reconstructive surgery.

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More information

Accepted/In Press date: 26 January 2015
e-pub ahead of print date: 7 February 2015
Published date: 13 April 2015
Keywords: short stem, primary stability, inter-subject variability
Organisations: Bioengineering Group

Identifiers

Local EPrints ID: 374445
URI: http://eprints.soton.ac.uk/id/eprint/374445
ISSN: 0021-9290
PURE UUID: 3d044461-669f-414b-9022-706c9aa7afaf
ORCID for Markus O. Heller: ORCID iD orcid.org/0000-0002-7879-1135
ORCID for Martin Browne: ORCID iD orcid.org/0000-0001-5184-050X

Catalogue record

Date deposited: 17 Feb 2015 14:48
Last modified: 17 Dec 2019 01:58

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Contributors

Author: M.T. Bah
Author: Junfen Shi
Author: Yanneck Suchier
Author: Fabien Lefebvre
Author: Philippe Young
Author: Leonard King
Author: Douglas G. Dunlop
Author: Mick Boettcher
Author: Edward Draper
Author: Martin Browne ORCID iD

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