A CT-image-based framework for the holistic analysis of cortical and trabecular bone morphology

This study introduces a standardized framework for the holistic analysis of cortical and trabecular bone structure. This method, although applicable to all bones of the skeleton, is particularly useful for irregular-shaped or small bones for which the application of traditional methods has been especially challenging. Traditional analyses have quantified cortical or trabecular structure in only selected regions of a bone, such as single cross-sections of cortical bone or volumes of interest of trabecular structure in epiphyses. The proposed method improves on these traditional methods by visualizing and quantifying the internal bony structure throughout the entire bone and in userdefined anatomical subregions. Here, we describe and demonstrate the method using high-resolution microtomographic scans of a first metacarpal of an orangutan, gorilla, chimpanzee and human. Using automated morphological filters, the cortical bone is defined and extracted from the underlying trabecular structure to create two 3D models, one of the cortex and one of the trabecular bone that can be analysed separately. We test the sensitivity of the morphological parameters used to create these 3D models, demonstrating that the parameters defined here are robust and can provide accurate measures of cortical thickness, relative bone density, trabecular orientation, trabecular thickness and degree of anisotropy. This new, holistic method is able to reveal morphological and functional information about bone loading that is obscured or ignored using traditional methods, thus providing more informed interpretations of behaviour in extant and fossil taxa. Thomas Gross. Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Gusshausstrasse 27-29, A-1040 Vienna, Austria. [email protected] Tracy L. Kivell. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig 04103, Germany and School of Anthropology and Conservation, University of Kent, Marlowe Building, Canterbury CT2 7NR, UK. [email protected] Matthew M. Skinner. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig 04103, Germany and Department of Anthropology, University College London, 14 Taviton Street, London WC1H 0BW, UK. [email protected] Huynh Nguyen. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig 04103, Germany. [email protected] PE Article Number: 17.3.33A Copyright: Palaeontological Association October 2014 Submission: 8 November 2013. Acceptance: 31 August 2014 Gross, Thomas, Kivell, Tracy L., Skinner, Matthew M., Nguyen, N. Huynh, and Pahr, Dieter H. 2014. A CT-image-based framework for the holistic analysis of cortical and trabecular bone morphology. Palaeontologia Electronica Vol. 17, Issue 3;33A; 13p; palaeo-electronica.org/content/2014/889-holistic-analysis-of-bone GROSS ET AL.: HOLISTIC ANALYSIS OF BONE Dieter H. Pahr. Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Gusshausstrasse 27-29, A-1040 Vienna, Austria. [email protected]