ABSTRACT
The bone tissue is a live regenerating and adapting tissue. During life the bone tissue continuously experience reinforce and resorption phenomenon, adapting the internal microstructure and the external shape to the surrounding stress conditions [1]. The first to suggest that there was a direct relation between the bone micro microstructure and the applied external mechanical load was Julius Wolff. The Wolff’s Law [2] established that trabecular (or cancellous) bone tends to be aligned with the principal stress directions. In the attempt to write new mathematical laws that explain the bone remodelling mechanism many other models have been developed. The “Theory of Adaptive Elasticity” [3] was probably the first complete consistent model, in which the authors assumed that strain controls the variation of bone apparent density, which is defined as mass per bulk volume of porous tissue, and consequently the bone elastic properties. Many further isotropic models have follow [4-6]. Initially these models developed for predicting trabecular architecture were based on the hypothesis that cancellous bone is a self-optimizing biological material seeking to maximize its own structural design [4, 7, 8]. The relationship between the bone mass and the local strain values in the bone tissue was obtained by minimizing the local strain-energy density (SDE), the objective remodelling function. More recently others have developed anisotropic models [9, 10], which are more close to reality as have been widely observed and measured experimentally [11, 12].
