title: Directional tortuosity as a predictor of modulus damage for vertebral cancellous bone.
abstract: There are many methods used to estimate the undamaged effective (apparent) moduli of cancellous bone as a function of bone volume fraction (BV/TV), mean intercept length(MIL), and other image based average microstructural measures. The MIL and BV/TV are both only functions of the cancellous microstructure and, therefore, cannot directly account for damage induced changes in the intrinsic trabecular hard tissue mechanical properties. Using a nonlinear finite element (FE) approximation for the degradation of effective modulus as a function of applied effective compressive strain, we demonstrate that a measurement of the directional tortuosity of undamaged trabecular hard tissue strongly predicts directional effective modulus (r2>0.90) and directional effective modulus degradation (r2>0.65). This novel measure of cancellous bone directional tortuosity has the potential for development into an anisotropic approach for calculating effective mechanical properties as a function of trabecular level material damage applicable to understanding how tissue microstructure and intrinsic hard tissue moduli interact to determine cancellous bone quality.
authors.forename: David P
authors.initials: DP
authors.lastname: Fyhrie
authors.forename: Roger
authors.initials: R
authors.lastname: Zauel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001696:Biomechanical Phenomena; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D016014:Linear Models; D008297:Male; D055595:Mechanical Phenomena; D008875:Middle Aged; D017711:Nonlinear Dynamics; D009929:Organ Size; D013904:Thoracic Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography; D055815:Young Adult