A NEW METHOD TO DETERMINE TRABECULAR BONE ELASTIC PROPERTIES AND LOADING USING MICROMECHANICAL FINITE-ELEMENT MODELS

The apparent mechanical behavior of trabecular bone depends on propert ies at the tissue or trabecular level. Many investigators have attempt ed to determine trabecular tissue properties and loading. However, acc uracy and applicability of all methods reported are limited. The small size of the trabeculae and a possible size effect are complicating fa ctors when using traditional testing methods on single trabeculae. Oth er methods reported, using models that describe the trabecular structu re, are of limited value because they consider bone as a repetitive st ructure in order to describe a reasonably large region of bone. The pr esent study introduces a new finite-element method strategy that enabl es analysis of reasonably large regions of trabecular bone in full det ail. The method uses three-dimensional serial reconstruction technique s to construct a large-scale FE model, by directly converting voxels t o elements. A 5 mm cube of trabecular bone was modeled in this way, re sulting in a FE model that consists of 296,679 elements. Special strat egies were developed to solve the set of equations that results from t he FE approach. Using this model in combination with experimental appa rent data taken from the literature, the upper and lower boundaries fo r the tissue modulus were calculated to be 10.1 and 2.23 GPa, respecti vely. From the local stress and strain distributions it was concluded that the deformation mode of the trabeculae in the present cube was pr edominantly in bending. It was concluded that the method developed off ers new perspectives for the study of trabecular bone.