Microtomography of Cortical Bone using a Synchrotron Source

M. Dalstra, P.M. Cattaneo (Denmark), F. Beckmann (Germany), and E.M. Hauge (Denmark)

Keywords

microtomography, cortical bone, osteon, remodelling, haversian systems, osteocyte

Abstract

Until now cortical bone has hardly been studied with microtomography, because its structural features are either too small to be detected using table-top CT systems or, due to beam hardening effects, too much is lost of the differences in the grey values to be able to properly identify them. By using a synchrotron radiation (SR) source with a monochromator both of the aforementioned problems are tackled. The aim of this study was therefore to investigate the structure of cortical bone with SR-based microtomography. Strips of cortical bone were scanned with a spatial resolution of 4 m. Individual osteons were clearly visible as concentric rings around haversian canals. The grey values are directly related to the degree of mineralisation and thus the darker an osteon appears, the less mineralised it is. Comparison with histological sections confirmed that these concentric rings are indeed osteons. By inverting threshold values, the cavities within the bone were visualised, revealing intricate networks of haversian canals and osteocyte lacunae. Furthermore, evidence of formation of new canals was found. SR-based microtomography provides new insights in cortical bone structure and its remodelling. This is the first time that 3D reconstructions have been made of the haversian network inside cortical bone.

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