Mechanical Contributions of the Cortical and Trabecular Compartments Contribute to Differences in Age-Related Changes in Vertebral Body Strength in Men and Women Assessed by QCT-Based Finite Element Analysis

Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research (Impact Factor: 6.83). 05/2011; 26(5):974-83. DOI: 10.1002/jbmr.287
Source: PubMed


The biomechanical mechanisms underlying sex-specific differences in age-related vertebral fracture rates are ill defined. To gain insight into this issue, we used finite element analysis of clinical computed tomography (CT) scans of the vertebral bodies of L3 and T10 of young and old men and women to assess age- and sex-related differences in the strength of the whole vertebra, the trabecular compartment, and the peripheral compartment (the outer 2 mm of vertebral bone, including the thin cortical shell). We sought to determine whether structural and geometric changes with age differ in men and women, making women more susceptible to vertebral fractures. As expected, we found that vertebral strength decreased with age 2-fold more in women than in men. The strength of the trabecular compartment declined significantly with age for both sexes, whereas the strength of the peripheral compartment decreased with age in women but was largely maintained in men. The proportion of mechanical strength attributable to the peripheral compartment increased with age in both sexes and at both vertebral levels. Taken together, these results indicate that men and women lose vertebral bone differently with age, particularly in the peripheral (cortical) compartment. This differential bone loss explains, in part, a greater decline in bone strength in women and may contribute to the higher incidence of vertebral fractures among women than men.

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    • "Cortical thickness slightly decreases with aging. Although most studies emphasize the important role of trabecular bone in age-related vertebral fragility, both old and new studies point to an important role for the cortical shell, particularly when trabecular bone volume is low, in elderly subjects [24] [25] [26] [27] "
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    • "Vertebral endplates embedded in polymethylmethcrylate (PMMA) (Crawford et al. 2003; 55 Liebschner et al. 2003; Buckley et al. 2007; Christiansen et al. 2011) are a gold standard but the 56 endplates can be removed to create vertebral sections (Ebbesen et al. 1999; Dall'Ara et al. 2011). 57 These two validated models compute compressive ultimate load and provide a better fracture risk 58 prediction than densitometric methods (Crawford et al. 2003; Buckley et al. 2007). "
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