Bone Material Properties and Skeletal Fragility

Abstract

Deformations of vertebrae and sudden fractures of long bones caused by essentially normal loading are a characteristic problem in osteoporosis. If the loading is normal, then the explanation for and prediction of unexpected bone failure lies in understanding the mechanical properties of the whole bone-which come from its internal and external geometry, the mechanical properties of the hard tissue, and from how well the tissue repairs damage. Modern QCT and MRI imaging systems can measure the geometry of the mineralized tissue quite well in vivo-leaving the mechanical properties of the hard tissue and the ability of bone to repair damage as important unknown factors in predicting fractures. This review explains which material properties must be measured to understand why some bones fail unexpectedly despite our current ability to determine bone geometry and bone mineral content in vivo. Examples of how to measure the important mechanical properties are presented along with some analysis of potential drawbacks of each method. Particular attention is given to methods useful to characterize the loss of bone toughness caused by mechanical fatigue, drug side effects, and damage to the bone matrix.

Bone quality changes associated with aging and disease: a review

“…Numerous techniques exist to measure these quality variables, reviewed elsewhere, along with a few newer techniques referenced later. Architecture and geometry can be measured by micro‐, nano‐, or peripheral‐computerized tomography and by nuclear magnetic resonance imaging . Bone turnover is generally measured by histomorphometry, although it can be approximated from urinary turnover‐markers .…”

“…Architecture and geometry can be measured by micro-, nano-, or peripheralcomputerized tomography and by nuclear magnetic resonance imaging. [5][6][7] Bone turnover is generally measured by histomorphometry, 8 although it can be approximated from urinary turnover-markers. 9 Macroscopic cortical porosity has been measured by microcomputed tomography (microCT) 10 MRI; 11 however, newer methods exist on the basis of Raman spectroscopy 12,13 and short-wave infrared Raman spectroscopy 14 that have also been applied to measure water content.…”

Cx43 Overexpression in Osteocytes Prevents Osteocyte Apoptosis and Preserves Cortical Bone Quality in Aging Mice

“…Bone quality depends not only on the geometry and microarchitecture of the bone but also on its material composition . Bone material properties include mineral content, collagen composition, and microdamage accumulation .…”

“…Bone quality depends not only on the geometry and microarchitecture of the bone but also on its material composition . Bone material properties include mineral content, collagen composition, and microdamage accumulation . Numerous studies have demonstrated the critical role that osteocytes play in sensing mechanical stimuli and coordinating targeted bone remodeling to repair damaged areas .…”

Even with rehydration, preservation in ethanol influences the mechanical properties of bone and how bone responds to experimental manipulation

“…There is growing recognition in the field of the importance of these mechanical measurements, as demonstrated by two recent review articles focused on understanding commonly measured mechanical properties in bone [1] and how to properly execute mechanical tests in small mouse bones to extract the most useful data [2]. This increased use of mechanical testing, particularly in genetic mouse models, is exciting but it comes with potential problems.…”