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Ng et al. Decreased bone turnover, aging and fracture risk



DOI:10.1038/bonekey.2016.45

Ng et al. studied the impact of aging on the bones of mice developed as a model of adynamic bone; this bone lesion is common in chronic kidney disease and in patients prescribed long-term anti-resorptive therapies. Adynamic bone is characterized by low turnover and this study sought to understand more about the impact on bone quality and risk of bone fracture.

Two groups of mice, (4 months vs 16 months) were treated with pamidronate and ganciclovir to stimulate the development of adyanamic bone. Microcomputed tomography, quantitative backscattered electron imaging, biomechanical testing and bone histomorphometry were used to assess bone quality while variations in bone matrix and mineralization were studied using Raman spectroscopy and powder X-ray diffraction.

Mice in both age-groups exhibited significantly reduced bone turnover. Older adynamic mice showed less age-related bone-loss compared to untreated age-matched controls but their bone mechanical properties deteriorated similarly, their cortical bone showed decreased toughness and they developed longer bone crystals and a more mature collagen matrix. These findings may provide useful insights into the type of fractures sustained by elderly patients with low bone-turnover due to long-term antiresorptive therapy.

Editor’s comment: The presented data do indeed support a significant age-related reduction in energy to failure of the femoral diaphysis in a mouse model of decreased bone turnover. Given the concomitant increase in cross-sectional area and the known parameter sensitivity of bending mechanics, the extrapolation of this finding to material properties must be interpreted with caution.


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