Disponible en ligne sur www.sciencedirect.com IRBM 34 (2013) 191–195 Original article Combined finite element model of human proximal femur behaviour considering remodeling and fracture R. Hambli a,∗ , C.-L. Benhamou b , R. Jennane a , E. Lespessailles b , W. Skalli c , S. Laporte c , J.-D. Laredo d , V. Bousson d , J. Zarka e a Prisme Institute/MMH, 8, rue Léonard-de-Vinci, 45072 Orléans cedex 2, France b Inserm U658, IPROS, CHR d’Orléans, 1, rue Porte-Madeleine, 45032 Orléans cedex 1, France c Arts et Métiers ParisTech, laboratoire de biomécanique, Paris, France d CNRS, laboratoire de recherches orthopédiques, université Paris 7, UMR CNRS 7052, B2OA, 10, avenue de Verdun, 75010 Paris, France e CADLM, 43, rue du Saule-Trapu, 91300 Massy, France Received 14 January 2013; received in revised form 17 January 2013; accepted 17 January 2013 Available online 16 March 2013 Abstract The purpose of this work was to develop a combined remodeling-to-fracture finite element model allowing for the combined simulation of human proximal femur remodeling under a given boundary conditions followed by the simulation of its fracture behaviour under quasi-static load. The combination of remodeling and fracture simulation into one unified model consists in considering that the femur properties resulting from the remodeling simulation correspond to the initial state for the fracture prediction. The remodeling model is based on a coupled strain and fatigue damage stimulus approach. The fracture model is based on continuum damage mechanics in order to predict the progressive fracturing process, which allows to predict the fracture pattern and the complete force-displacement curve under quasi-static load. To investigate the potential of the proposed unified remodeling-to-fracture model, we performed remodeling simulations on a 3D proximal femur model for a duration of 365 days followed by a side fall fracture simulation reproducing. © 2013 Published by Elsevier Masson SAS. 1. Introduction Healthy human femur adapts its strength and mass to its mechanical use since it endures daily loads. Osteoblasts and osteoclasts cells respectively add and resorb bone during the remodeling process as a response to the mechanical stimulus sensed by osteocytes [1–3]. Results of bone remodeling (mass, microarchitecture and bone material properties of both cancel- lous and cortical bone) control bone stiffness and strength, which can be assessed by the ultimate force provoking fracture at organ level [4,5]. In clinical practice, current fracture prediction methods are based on the mineral content of bone at a particular instant and do not account for its adaptation, which will occur over time. The prediction of fracture risk could therefore be under or over estimated thereby leading to inaccurate prognoses and ∗ Corresponding author. E-mail address: ridha.hambli@univ-orleans.fr (R. Hambli). unnecessary costs. Assessing the mechanical properties of human femur due to a given remodeling cycle and thus predict- ing its failure is still a challenge that can be addressed using the finite element (FE) method. Over the last years, a large number of FE models have been developed to predict sepa- rately bone remodeling and bone fracture [6,7]. Cristofolini et al. [8] reported that the development of enhanced multiscale bone fracture prediction models, requires coupling separated models including remodeling and fracture into a full multiscale model which is still a work in progress. Such FE models would allow clinicians to directly predict bone strength, estimate the risk of fracture and implement relevant preventative treatments for patients. The aim of the current work was to develop an combined R-F FE model to simulate the bone remodeling process under given boundary conditions and duration of time followed by its fracture simulation under a given boundary conditions (side fall, one- legged stance load) in the quasi-static regime (low strain rate). To check the validity of the combined model, we performed remodeling simulation on a 3D proximal femur model for a 1959-0318/$ – see front matter © 2013 Published by Elsevier Masson SAS. http://dx.doi.org/10.1016/j.irbm.2013.01.011