The effect of interfacial parameters on cup-bone relative micromotions: a finite element investigation

Hdl Handle:
http://hdl.handle.net/10149/58217
Title:
The effect of interfacial parameters on cup-bone relative micromotions: a finite element investigation
Authors:
Spears, I. R. (Iain); Pfleiderer, M. (Martin); Schneider, E. H. (Erich); Hille, E. (Ekkehard); Morlock, M. M. (Michael)
Affiliation:
Technical University of Harburg. Biomechanics Section. Germany; DePuy International. United Kingdom; AO Research Institute. Switzerland; General Hospital Barmbek. Germany; University of Teesside. School of Social Science. Department of Sport Science.
Citation:
Spears, I. R. et al. (2001) 'The effect of interfacial parameters on cup-bone relative micromotions: a finite element investigation', Journal of Biomechanics, 34 (1), pp.113-120.
Publisher:
Elsevier
Journal:
Journal of Biomechanics
Issue Date:
Jan-2001
URI:
http://hdl.handle.net/10149/58217
DOI:
10.1016/S0021-9290(00)00112-3
Abstract:
Achieving stability is a prerequisite for allowing bone to grow into the porous surface of non-cemented acetabular cups. The purpose of this study is to estimate the effects of interfacial characteristics on relative cyclical micromotion between cup and bone during gait in the immediate postoperative phase. The technique used is finite element analysis. Six models with different interfacial characteristics are created in order to study the effects of fixation technique. These include representation of a 1mm press-fit, 2mm press-fits (with and without an initial polar gap) and exact-fit conditions (with and without additional screw fixation). Although direct validation of the model has not been performed, the calculated micromotions under a static load of 1112N are compared with appropriate experimental data. Generally, the model tends to underestimate micromotion and this underestimate is significant in the case of relative surface-normal micromotion in polar regions for models with low- and no-interference. The most likely cause of this significant underestimate is a failure of the model to accurately represent penetration of rough contacting surfaces under compression. Other types of micromotion, although low, are within standard deviations reported by Kwong et al. (1994 Journal of Arthroplasty 9, 163-170). Quasi-static joint contact and muscle forces, representative of the stance phase of gait are then applied and maximum micromotions are found to occur consistently prior to toe off: this being the point of maximum force. With regard to the press-fit simulations, good cup-bone contact in the superior region of the interface is required for stability and the greatest micromotions occur in the models with the larger interference and larger polar gaps. In contrast to the press-fit models, muscle activity in exact-fit models influences the calculations. Specifically, the early activity of m.semimembranosus modelled causes opening of the peripheral seal. Taken together it is found that polar gaps reduce the stability of the model and lack of pre-compresssion in the periphery allows this region of the interface to be opened up.
Type:
Article
Keywords:
acetabular cups; finite elements; primary stability; bone
ISSN:
0021-9290
Rights:
Author can archive post-print (ie final draft post-refereeing). For full details see http://www.sherpa.ac.uk/romeo/ [Accessed 14/01/2010]
Citation Count:
30 [Scopus, 14/01/2010]

Full metadata record

DC FieldValue Language
dc.contributor.authorSpears, I. R. (Iain)-
dc.contributor.authorPfleiderer, M. (Martin)-
dc.contributor.authorSchneider, E. H. (Erich)-
dc.contributor.authorHille, E. (Ekkehard)-
dc.contributor.authorMorlock, M. M. (Michael)-
dc.date.accessioned2009-04-01T10:46:14Z-
dc.date.available2009-04-01T10:46:14Z-
dc.date.issued2001-01-
dc.identifier.citationJournal of Biomechanics; 34 (1): 113-120-
dc.identifier.issn0021-9290-
dc.identifier.doi10.1016/S0021-9290(00)00112-3-
dc.identifier.urihttp://hdl.handle.net/10149/58217-
dc.description.abstractAchieving stability is a prerequisite for allowing bone to grow into the porous surface of non-cemented acetabular cups. The purpose of this study is to estimate the effects of interfacial characteristics on relative cyclical micromotion between cup and bone during gait in the immediate postoperative phase. The technique used is finite element analysis. Six models with different interfacial characteristics are created in order to study the effects of fixation technique. These include representation of a 1mm press-fit, 2mm press-fits (with and without an initial polar gap) and exact-fit conditions (with and without additional screw fixation). Although direct validation of the model has not been performed, the calculated micromotions under a static load of 1112N are compared with appropriate experimental data. Generally, the model tends to underestimate micromotion and this underestimate is significant in the case of relative surface-normal micromotion in polar regions for models with low- and no-interference. The most likely cause of this significant underestimate is a failure of the model to accurately represent penetration of rough contacting surfaces under compression. Other types of micromotion, although low, are within standard deviations reported by Kwong et al. (1994 Journal of Arthroplasty 9, 163-170). Quasi-static joint contact and muscle forces, representative of the stance phase of gait are then applied and maximum micromotions are found to occur consistently prior to toe off: this being the point of maximum force. With regard to the press-fit simulations, good cup-bone contact in the superior region of the interface is required for stability and the greatest micromotions occur in the models with the larger interference and larger polar gaps. In contrast to the press-fit models, muscle activity in exact-fit models influences the calculations. Specifically, the early activity of m.semimembranosus modelled causes opening of the peripheral seal. Taken together it is found that polar gaps reduce the stability of the model and lack of pre-compresssion in the periphery allows this region of the interface to be opened up.-
dc.publisherElsevier-
dc.rightsAuthor can archive post-print (ie final draft post-refereeing). For full details see http://www.sherpa.ac.uk/romeo/ [Accessed 14/01/2010]-
dc.subjectacetabular cups-
dc.subjectfinite elements-
dc.subjectprimary stability-
dc.subjectbone-
dc.titleThe effect of interfacial parameters on cup-bone relative micromotions: a finite element investigation-
dc.typeArticle-
dc.contributor.departmentTechnical University of Harburg. Biomechanics Section. Germany; DePuy International. United Kingdom; AO Research Institute. Switzerland; General Hospital Barmbek. Germany; University of Teesside. School of Social Science. Department of Sport Science.-
dc.identifier.journalJournal of Biomechanics-
ref.assessmentRAE 2008-
ref.citationcount30 [Scopus, 14/01/2010]-
or.citation.harvardSpears, I. R. et al. (2001) 'The effect of interfacial parameters on cup-bone relative micromotions: a finite element investigation', Journal of Biomechanics, 34 (1), pp.113-120.-
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