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Goff et al. Cancellous bone failure and its relationship to fragility fractures
DOI:10.1038/bonekey.2016.9
In order to understand the root causes of fragility fractures, Goff et al. studied the processes involved in tissue microdamage within cancellous bone.
Three-dimensional evaluations of microdamage in cancellous bone samples obtained from the vertebra of 10 male and 6 female elderly human donors were made during sub-failure cyclic compressive loading experiments.
Almost three-quarters of all the microdamage that occurred was seen in the 10% largest microdamage sites. Most of the microdamage was more than 30 μm from the surface of trabecular bone, indicating that most of the damage to cancellous bone occurs within the interstitial tissue. The authors also noted that microdamage was more likely to occur close to other (non-trabecular) bone surfaces than to regions in the vicinity of resorption cavities. This challenges the previous theory that fatigue failure of cancellous bone is due to an increase in localized stress at those cavities.
Editor’s comment: The authors show that fatigue micro-damage in vertebral cancellous bone accumulates primarily in the older bone structural units located in the core of the trabeculae but not in the vicinity of resorption spaces. The first finding fits nicely with our knowledge of cortical bone, but the second calls for a careful interpretation as the stress distribution imposed in the ex vivo tests may diverge from the physiological ones that contributed to the remodeling of the biopsied architecture.
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