Experimental validation of numerically predicted strain and micromotion in intact and implanted composite hemi-pelvises

Abstract

The failure mechanisms of acetabular prostheses may be investigated by understanding the changes in load transfer due to implantation, and analysis of the implant-bone micromotion. Computational finite element (FE) models allow detailed mechanical analysis of the implant-bone structure, but their validity must be assessed as part of a verification process before they can be employed in pre-clinical investigations. To this end, in the present study, FE models of composite hemi-pelvises, intact and implanted with an acetabular cup, were experimentally verified. Strains and implant-bone micromotions in the hemi-pelvises were compared with those predicted by the equivalent FE models. Regression analysis indicated close agreement between the measured and FE strains, with a high correlation coefficient (0.95-0.98), a low standard error of the estimate (36-53µ?) and a low error in regression slope (7-11%). Measured micromotions along three orthogonal directions were small, less than 30µm, whereas the FE predicted values were found to be less than 85µm. Although the trends were similar, the observed deviations may be due to estimation of the interfacial press-fit used in the FE model, and additional artefacts in experimental micromotion measurement which are avoided in the FE model. This supports the FE model as a valid predictor of the experimentally measured strain in the composite pelvis models, confirming its suitability for further computational investigations on acetabular prostheses.

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Identifiers

ORCID for A.S. Dickinson: orcid.org/0000-0002-9647-1944

ORCID for M. Browne: orcid.org/0000-0001-5184-050X

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