Characterisation of Trabecular Bone Structure - Skeletal Aging and Osteoporosis: Biomechanics and Mechanobiology - page 46

perforation and trabecular thinning, to a greater or lesser degree [ 9 ]. However,
significant trabecular bone loss is likely to occur in all individuals over the age of
60 and the degree to which this bone loss contributes to an increase in fracture risk
is dependent on multiple factors, including but not exclusively, peak bone mass,
degree of sarcopenia, propensity to falls and sunlight exposure [ 45 ]. At the bone
level alone, skeletal site, is an important risk factor, where the amount of bone, the
trabecular bone architecture and the cortical bone morphological properties differs
markedly at different sites [ 4 ].
8 Summary
A great deal of the knowledge of trabecular bone structure has been elucidated
from quantitative methods developed for analysis of histological sections. From
the pioneering work of Harold Frost in the 1960s to the present, the complex
architecture of trabecular bone has been acknowledged as a three-dimensional
entity, which has been optimized for its primary function of ensuring the habitual
loads extant on the skeleton do not allow it to fracture. Despite the practical
difficulties of describing a 3D structure from 2D images, workers in this field
have developed and utilized powerful quantitative tools, collectively known
as bone histomorphometry. These tools have provided quantitative character-
ization of the dimensions of trabeculae, the spatial arrangement between
trabeculae the cellular dynamics at trabecular surfaces and the dynamics of bone
mineralization.
While ex vivo investigations utilizing histomorphometry have provided
comprehensive characterisation of trabecular bone structure and determined
skeletal variation and morphological properties these observations have provided
an understanding of why and how fractures can occur but not in whom they are
going to occur. The X-ray-based imaging tools available today promise to enable
in vivo study of individuals at equivalent spatial resolution to histology or ex
vivo micro-CT imaging. The suite of tools available for the analysis of trabec-
ular bone as a 3D structure has been significantly expanded with the develop-
ment of tools that can isolate individual trabecular elements, enabling the
morphology of these structures to be measured. Together with finite-element-
based analysis, apparent mechanical properties can be obtained at the level of
individual trabecular elements to fully characterise the ability of the structure to
resist loads under varying conditions.
Acknowledgments The authors acknowledge the staff of the Bone and Joint Research
Laboratory, SA Pathology for their skill in sample preparation and quantitative analyses and The
National Health and Medical Research Council, Australia for grant funding.