Foreword: Calcified Tissue International and Musculoskeletal Research Special Issue

Excerpt

Skeletal fragility, and to a large extent the risk of fracture, is dependent on three general properties of a bone: the amount of bone (mass), the way the mass is distributed (architecture/geometry), and the material properties (characteristics of the mineral, collagen, noncollagenous proteins, skeletal hydration, and interaction among these constituents) of the tissue that compose the bone (Fig. 1). Of these three broad characteristics, bone mass has received the greatest attention as a predictor of fracture in large part because it is the easiest to measure in a clinical setting. DEXA measurements of bone mineral density (BMD) have become the standard measure of skeletal health, and alone are used as the definition for pathology: one is diagnosed with osteoporosis if the BMD is greater than 2.5 standard deviations below the young adult mean for a Caucasian woman, regardless of other compensatory characteristics of the bone that may offset the lower BMD. Even so, most scientists who study bone understand the importance of architecture, both the connectivity of the trabecular lattice, as well as the importance of cortical width, thickness, and porosity to bone’s rigidity. Architectural features are not completely independent of bone mass (e.g., loss of bone will affect trabecular connectivity), but they can be (section modulus can increase even as bone mass declines). Thus, BMD does not provide a complete picture of fracture risk. Moreover, architectural features are more difficult to measure in a clinical setting and only recently have they been utilized, in combination with BMD, to try to assess fracture risk. One example of this is the recent use of the trabecular bone score (TBS), which integrates trabecular texture analysis with BMD values.

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