Incorporating tissue anisotropy and heterogeneity in finite element models of trabecular bone altered predicted local stress distributions

Abstract

Trabecular bone is composed of organized mineralized collagen fibrils, which results in heterogeneous and anisotropic mechanical properties at the tissue level. Recently, biomechanical models computing stresses and strains in trabecular bone have indicated a significant effect of tissue heterogeneity on predicted stresses and strains. However, the effect of the tissue-level mechanical anisotropy on the trabecular bone biomechanical response is unknown. Here, a computational method was established to automatically impose physiologically relevant orientation inherent in trabecular bone tissue on a trabecular bone microscale finite element model. Spatially varying tissue-level anisotropic elastic properties were then applied according to the bone mineral density and the local tissue orientation. The model was used to test the hypothesis that anisotropy in both homogeneous and heterogeneous models alters the predicted distribution of stress invariants. Linear elastic finite element computations were performed on a 3 mm cube model isolated from a microcomputed tomography scan of human trabecular bone from the distal femur. Hydrostatic stress and von Mises equivalent stress were recorded at every element, and the distributions of these values were analyzed. Anisotropy reduced the range of hydrostatic stress in both tension and compression more strongly than the associated increase in von Mises equivalent stress. The effect of anisotropy was independent of the spatial redistribution high compressive stresses due to tissue elastic heterogeneity. Tissue anisotropy and heterogeneity are likely important mechanisms to protect bone from failure and should be included for stress analyses in trabecular bone.

Heterogeneous Tissue Modulus Improved Prediction of Mechanical Behavior in Osteoporotic Vertebral Cancellous Bone

“…Finite element models incorporating intra-specimen material heterogeneity performed only marginally better than specimen-specific homogeneous models. The crucial factor in improving model performance -specimen-specificity or heterogeneity -is disputed [39][40][41][42][43][44], although our results appear to support specimen-specificity. However, the assumption of purely elastic or linear deformation in FE models of cancellous bone may limit the efficacy of incorporating heterogeneity since linear behavior at the apparent level in vivo may involve some nonlinear behavior at the tissue level.…”

Cortical and trabecular bone structure of the hominoid capitate

“…Homo and Pongo had higher DA in the proximal capitate compared to the distal segment, which statistically separated them from the knuckle‐walking taxa. High DA is correlated with strength along predictable loading trajectories within joints (Cotter et al, 2009 ; Hammond et al, 2018 ; Hart et al, 2017 .) In Homo , DA in the proximal capitate may be explained by load predictability as the DTM constitutes the path of motion in a large proportion of daily activities (Brigstocke et al, 2014 ; Crisco et al, 2005 ; Kaufman‐Cohen et al, 2019 ; Moritomo et al, 2014 ; Schuind et al, 1994 ).…”

“…and not yet fully understood by bone biologists. et al, 2014) and other skeletal elements, including the talus (Desilva & Devlin, 2012;Tsegai et al, 2013), humerus (Kivell et al, 2018) and femur (Georgiou et al, 2019 (Cotter et al, 2009;Hammond et al, 2018;Hart et al, 2017. ) In Homo, DA in the proximal capitate may be explained by load predictability as the DTM constitutes the path of motion in a large proportion of daily activities (Brigstocke et al, 2014;Crisco et al, 2005;Kaufman-Cohen et al, 2019;Moritomo et al, 2014;Schuind et al, 1994).…”

Mapping Spatially Distributed Material Properties in Finite Element Models of Plant Tissue Using Computed Tomography

“…First, this method provides a new way to create models of plant behavior that account for the variation in material stiffnesses. This should enable a deeper exploration of the stress states within a plant tissues than is possible when using simple, homogenous material modeling (Hammond et al 2018) . These results were obtained in Abaqus 2017.…”