The Impact of Voxel Size-Based Inaccuracies on the Mechanical Behavior of Thin Bone Structures

Abstract

Computed tomography (CT)-based measures of skeletal geometry and material properties have been widely used to develop finite element (FE) models of bony structures. However, in the case of thin bone structures, the ability to develop FE models with accurate geometry derived from clinical CT data presents a challenge due to the thinness of the bone and the limited resolution of the imaging devices. The purpose of this study was to quantify the impact of voxel size on the thickness and intensity values of thin bone structure measurements and to assess the effect of voxel size on strains through FE modeling. Cortical bone thickness and material properties in five thin bone specimens were quantified at voxel sizes ranging from 16.4 to 488μm. The measurements derived from large voxel size scans showed large increases in cortical thickness (61.9-252.2%) and large decreases in scan intensity (12.9-49.5%). Maximum principal strains from FE models generated using scans at 488μm were decreased as compared to strains generated at 16.4μm voxel size (8.6-64.2%). A higher level of significance was found in comparing intensity (p=0.0001) vs. thickness (p=0.005) to strain measurements. These findings have implications in developing methods to generate accurate FE models to predict the biomechanical behavior of thin bone structures.