Bone quality revisited: Fractures, structural hierarchy, and multiscale bone imaging Event

Although bone mineral density (BMD) is clinically used as a surrogate marker for bone strength, its power to predict fracture is only moderate. Moreover, the risk of fractures increases rapidly with age, which can be explained by a reduced BMD only to a limited extent.

The concept of bone quality has thus been established and utilised to explain contributions to bone’s resistance to fracture, which are commonly not attributed to BMD. However, bone quality is a loosely defined term, incorporating factors such as geometry, microarchitecture, cortical porosity, damage accumulation or material properties of the bone tissue, which are not assessed (routinely) in clinical practice, although they are known to change with age and due to osteoporosis.

To make matters worse, BMD and many of these factors are actually entangled and they span a wide range of length scales, reflecting the hierarchical organisation of bone tissue. On this account, determinants of fracture resistance need to be evaluated optimally at multiple levels of bone organisation through multiscale imaging. Here, we will focus particularly on high-resolution (3D) imaging approaches to assess bone tissue on a microstructural, ultrastructural and material properties level, to assess bone strength in the perspective of improving fracture risk assessment.