title: Micro-CT based finite element models of cancellous bone predict accurately displacement once the boundary condition is well replicated: A validation study.
abstract: Non-destructive 3D micro-computed tomography (microCT) based finite element (microFE) models are used to estimate bone mechanical properties at tissue level. However, their validation remains challenging. Recent improvements in the quantification of displacements in bone tissue biopsies subjected to staged compression, using refined Digital Volume Correlation (DVC) techniques, now provide a full field displacement information accurate enough to be used for microFE validation. In this study, three specimens (two humans and one bovine) were tested with two different experimental set-ups, and the resulting data processed with the same DVC algorithm. The resulting displacement vector field was compared to that predicted by microFE models solved with three different boundary conditions (BC): nominal force resultant, nominal displacement resultant, distributed displacement. The first two conditions were obtained directly from the measurements provided by the experimental jigs, whereas in the third case the displacement field measured by the DVC in the top and bottom layer of the specimen was applied. Results show excellent relationship between the numerical predictions (x) and the experiments (y) when using BC derived from the DVC measurements (UX: y=1.07x-0.002, RMSE: 0.001mm; UY: y=1.03x-0.001, RMSE: 0.001mm; UZ: y=x+0.0002, RMSE: 0.001 mm for bovine specimen), whereas only poor correlation was found using BCs according to experiment set-ups. In conclusion, microFE models were found to predict accurately the vectorial displacement field using interpolated displacement boundary condition from DVC measurement.
authors.affiliation: Department of Mechanical Engineering and INSIGNEO Institute for in silico Medicine, University of Sheffield, UK.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Human Metabolism and INSIGNEO Institute for in silico Medicine, University of Sheffield, UK.
authors.forename: Enrico
authors.initials: E
authors.lastname: Dall Ara
authors.affiliation: Institute for Bioengineering, School of Engineering, The University of Edinburgh, UK.
authors.forename: Erika
authors.initials: E
authors.lastname: Sales
authors.affiliation: Institute for Bioengineering, School of Engineering, The University of Edinburgh, UK.
authors.forename: Krishnagoud
authors.initials: K
authors.lastname: Manda
authors.affiliation: Department of Orthopaedics, The University of Edinburgh, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Wallace
authors.affiliation: Institute for Bioengineering, School of Engineering, The University of Edinburgh, UK.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Pankaj
authors.affiliation: Department of Mechanical Engineering and INSIGNEO Institute for in silico Medicine, University of Sheffield, UK. Electronic address: m.viceconti@shef.ac.uk.
authors.forename: Marco
authors.initials: M
authors.lastname: Viceconti
mesh_terms: D000818:Animals; D000071556:Cancellous Bone / Q000502:physiology*; D002417:Cattle; D020342:Finite Element Analysis; D006801:Humans; D055595:Mechanical Phenomena; D055114:X-Ray Microtomography
keywords: Cancellous bone; DVC; MicroCT; Validation; microFE