Methods for Assessing Bone Quality: A Review

Bone mass, geometry, and tissue material properties contribute to bone structural integrity. Thus, bone strength arises from both bone quantity and quality. Bone quality encompasses the geometric and material factors that contribute to fracture resistance. This review presents an overview of the methods for assessing bone quality across multiple length scales, their outcomes, and their relative advantages and disadvantages. A PubMed search was conducted to identify methods related to bone mechanical testing, imaging, and compositional analysis. Using various exclusion criteria, articles were selected for inclusion. Methods for assessing mechanical properties include whole-bone, bulk tissue, microbeam, and micro- and nanoindentation testing techniques. Outcomes include structural strength and material modulus. Advantages include direct assessment of bone strength; disadvantages include specimen destruction during testing. Methods for characterizing bone geometry and microarchitecture include quantitative CT, high-resolution peripheral quantitative CT, high-resolution MRI, and micro-CT. Outcomes include three-dimensional whole-bone geometry, trabecular morphology, and tissue mineral density. The primary advantage is the ability to image noninvasively; disadvantages include the lack of a direct measure of bone strength. Methods for measuring tissue composition include scanning electron microscopy, vibrational spectroscopy, nuclear magnetic resonance imaging, and chemical and physical analytical techniques. Outcomes include mineral density and crystallinity, elemental composition, and collagen crosslink composition. Advantages include the detailed material characterization; disadvantages include the need for a biopsy. Although no single method can completely characterize bone quality, current noninvasive imaging techniques can be combined with ex vivo mechanical and compositional techniques to provide a comprehensive understanding of bone quality.