A method to estimate cadaveric femur cortical strains during fracture testing using digital image correlation

Timothy Rossman, Susheil Uthamaraj, Asghar Rezaei, Sean McEligot, Hugo Giambini, Iwona Jasiuk, Michael J. Yaszemski, Lichun Lu, Dan Dragomir-Daescu

Research output: Contribution to journalArticle

Abstract

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral surface obtained from mechanical testing. This optical method requires a texture of many contrasting fiduciary marks on a solid white background for accurate tracking of surface deformation as loading is applied to the specimen. Immediately prior to testing, the surface of interest in the camera view is painted with a water-based white primer and allowed to dry for several minutes. Then, a black paint is speckled carefully over the white background with special consideration for the even size and shape of the droplets. Illumination is carefully designed and set such that there is optimal contrast of these marks while minimizing reflections through the use of filters. Images were obtained through high speed video capture at up to 12,000 frames/s. The key images prior to and including the fracture event are extracted and deformations are estimated between successive frames in carefully sized interrogation windows over a specified region of interest. These deformations are then used to compute surface strain temporally during the fracture test. The strain data is very useful for identifying fracture initiation within the femur, and for eventual validation of proximal femur fracture strength models derived from Quantitative Computed Tomography-based Finite Element Analysis (QCT/FEA).

Original languageEnglish (US)
Article numbere54942
JournalJournal of Visualized Experiments
Volume2017
Issue number127
DOIs
StatePublished - Sep 14 2017

Keywords

  • Bioengineering
  • Bone preparation protocol
  • Digital image correlation
  • Fall on the hip
  • Femoral fracture
  • Hip biomechanics
  • Issue 127
  • Strain measurement

ASJC Scopus subject areas

  • Neuroscience(all)
  • Chemical Engineering(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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  • Cite this

    Rossman, T., Uthamaraj, S., Rezaei, A., McEligot, S., Giambini, H., Jasiuk, I., Yaszemski, M. J., Lu, L., & Dragomir-Daescu, D. (2017). A method to estimate cadaveric femur cortical strains during fracture testing using digital image correlation. Journal of Visualized Experiments, 2017(127), [e54942]. https://doi.org/10.3791/54942