title: Multiscale investigation of the functional properties of the human femur.
abstract: The mechanical strength of human bones has often been investigated in the past. Bone failure is related to musculoskeletal loading, tissue properties, bone metabolism, etc. This is intrinsically a multiscale problem. However, organ-level performance in most cases is investigated as a separate problem, incorporating only part (if any) of the information available at a higher scale (body level) or at a lower one (tissue level, cell level). A multiscale approach is proposed, where models available at different levels are integrated. A middle-out strategy is taken: the main model to be investigated is at the organ level. The organ-level model incorporates as an input the outputs from the body-level (musculoskeletal loads), tissue-level (constitutive equations) and cell-level models (bone remodelling). In this paper, this approach is exemplified by a clinically relevant application: fractures of the proximal femur. We report how a finite-element model of the femur (organ level) becomes part of a multiscale model. A significant effort is related to model validation: a number of experiments were designed to quantify the model's sensitivity and accuracy. When possible, the clinical accuracy and the clinical impact of a model should be assessed. Whereas a large amount of information is available at all scales, only organ-level models are really mature in this perspective. More work is needed in the future to integrate all levels fully, while following a sound scientific method to assess the relevance and validity of such an integrated model.
authors.affiliation: Istituto Ortopedico Rizzoli, Via di Barbiano, 1/10, 40136 Bologna, Italy. cristofolini@techno.ior.it
authors.forename: Luca
authors.initials: L
authors.lastname: Cristofolini
authors.forename: Fulvia
authors.initials: F
authors.lastname: Taddei
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Baleani
authors.forename: Fabio
authors.initials: F
authors.lastname: Baruffaldi
authors.forename: Susanna
authors.initials: S
authors.lastname: Stea
authors.forename: Marco
authors.initials: M
authors.lastname: Viceconti
mesh_terms: D000818:Animals; D019245:Compressive Strength; D003198:Computer Simulation; D004548:Elasticity; D005269:Femur / Q000502:physiology*; D008954:Models, Biological; D013312:Stress, Physiological; D013718:Tensile Strength; D016474:Weight-Bearing / Q000502:physiology