Th* (r?=?0.47, p?=?.03), Ct.Th (r?=?0.64, p?=?.002), and Ct.Po (r?=?0.60, p?=?.004; Fig. 3). Ct.Po was significantly and positively correlated with Ct.Th (r?=?0.91, p?<?.0001). Residual strength averaged 89%????19% (range 47% to 121%) of initial values. Residual strength was not correlated with bone mass (ie, BMD, BMC, and BV/TV) or with initial mechanical behavior. In addition, residual strength was significantly and positively correlated with Tb.N* (r?=?0.50, p?=?.02) and significantly and negatively correlated with Tb.Sp* and Tb.Sp*SD (r?=??0.50 and ?0.55, p?=?.02 and p?=?.011, respectively; Fig. 3). For 6 vertebrae, postfracture failure load increased rather than decreased [residual strength?=?111%????8% (range 101% to 121%) versus 81%????15% (range: 47% to 99%) for the 15 other ones]. These 6 vertebrae did not differ from the 15 other ones in term of age, sex, vertebral body height, and bone mass. However, Pexidartinib in these 6 vertebrae, Tb.N* was significantly higher (p?=?.02) and Tb.Sp* and Tb.Sp*SD were significantly lower than the 15 other vertebrae (p?=?.02 and p?=?.03, respectively; Fig. 4). Residual stiffness averaged 47%????18% (range 24% to 98%) of initial values. Residual stiffness was Y-27632 cost not correlated with bone mass (ie, BMD, BMC, and BV/TV) or with initial mechanical behavior. In addition, residual stiffness was significantly and positively correlated with Tb.Th* (r?=?0.58, p?=?.006) and significantly and negatively correlated with Ct.Curv (|r|?=??0.52, p?=?.015; Fig. 3). To our knowledge, no study to date has directly assessed the ability of a whole vertebral body to carry load after a simulated mild fracture (ie, SQ grade 1). Moreover, the determinants of this postfracture load-bearing capacity are critical but poorly understood.9, 10 We found that after sustaining an initial fracture, vertebral failure load and stiffness were decreased, whereas work to failure was increased. Although postfracture mechanical parameters were highly correlated with their initial counterparts, 47% to 71% of CHIR-99021 cell line the variation in the postfracture mechanical behavior was explained by determinants other than the initial mechanical parameters, namely, microarchitecture. The vertebral body consists of a trabecular bone center surrounded by a thin and porous cortical shell or perhaps trabecular condensation.15, 19, 20 This complex structure can be idealized and modeled as a cellular solid such as a natural honeycomb-like material close to an open-cell plastic foam.21 Indeed, the compressive load-displacement curve of trabecular bone is typical of this model.21?C23 The mechanical behavior shows a linear-elastic regime followed by a plateau of roughly constant load leading into a final regime of steeply rising stress. Each regime is associated with a mechanism of deformation.22 On the first loading, the cell walls bend, giving linear elasticity, but when a critical stress is reached, the cells begin to collapse.
Views 1 Votes 0 Comment 0