Combining micro computed tomography and three-dimensional registration to evaluate local strains in shape memory scaffolds

Appropriate mechanical stimulation of bony tissue enhances osseointegration of load-bearing implants. Uniaxial compression of porous implants locally results in tensile and compressive strains. Their experimental determination is the objective of this study. Selective laser melting is applied to produce open-porous NiTi scaffolds of cubic units. To measure displacement and strain fields within the compressed scaffold, the authors took advantage of synchrotron radiation-based micro computed tomography during temperature increase and non-rigid three-dimensional data registration. Uniaxial scaffold compression of 6% led to local compressive and tensile strains of up to 15%. The experiments validate modeling by means of the finite element method. Increasing the temperature during the tomography experiment from 15 to 37 °C at a rate of 4 K h−1, one can locally identify the phase transition from martensite to austenite. It starts at ∼24 °C on the scaffolds bottom, proceeds up towards the top and terminates at ∼34 °C on the periphery of the scaffold. The results allow not only design optimization of the scaffold architecture, but also estimation of maximal displacements before cracks are initiated and of optimized mechanical stimuli around porous metallic load-bearing implants within the physiological temperature range.

Keywords

NiTi, Scaffold Compression, Variable Temperature Tomography, Digital Volume Correlation, Three-Dimensional Displacement Field

Subject (DDC)

600 - Technik, Medizin, angewandte Wissenschaften

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ISBN

ISSN

1742-7061
1878-7568

Language

English

Created during FHNW affiliation

Yes

Strategic action fields FHNW

Publication status

Published

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Peer review of the complete publication

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Closed

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Citation

BORMANN, Therese, Georg SCHULZ, Hans DEYHLE, Felix BECKMANN, Michael DE WILD, Jürg KÜFFER, Christoph MÜNCH, Waldemar HOFFMANN und Bert MÜLLER, 2014. Combining micro computed tomography and three-dimensional registration to evaluate local strains in shape memory scaffolds. Acta Biomaterialia. Februar 2014. Bd. 10, Nr. 2, S. 1024–1034. DOI 10.1016/j.actbio.2013.11.007. Verfügbar unter: https://irf.fhnw.ch/handle/11654/45805

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