Raloxifene enhances material- level mechanical properties of femoral cortical and trabecular bone
Raloxifene enhances material- level mechanical properties of femoral cortical and trabecular bone
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DOI：
10.1210/en.2007-0275
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发表时间：
2007-08-01
期刊：
影响因子：
4.8
通讯作者：
Burr, David B.
中科院分区：
文献类型：
--
作者：
Allen, Matthew R.;Hogan, Harry A.;Burr, David B.
我们之前已经证明雷洛昔芬增强了犬椎骨的机械性能，与骨量变化无关，表明雷洛昔芬对材料水平的机械性能有积极影响。本研究的目的是确定雷洛昔芬对比格犬股骨松质骨和皮质骨材料水平力学性能的单独影响。每日经口给药一次溶剂或雷洛昔芬（0.50 mg/ kg中心点d），持续1年。使用减少的压板压缩，在股骨颈处测量松质骨机械性能，该方法允许在不取芯样本的情况下测试松质骨。使用单调和动态（循环松弛）四点弯曲试验，对股骨干加工的棱柱形梁样本进行皮质骨性能评估。与溶剂处理动物相比，雷洛昔芬处理动物的小梁骨具有显著更高的极限应力（+ 130%）、模量（+ 89%）和韧性（+ 152%）。雷洛昔芬给药动物的皮质骨韧性（+ 62%）显著高于溶剂组，主要是由于骨折后位移增加（+ 100%）。在皮质骨循环松弛试验期间，两组之间的刚度损失百分比没有显著差异。这些结果与这些动物椎骨的先前数据一致，表明雷洛昔芬对生物力学特性具有积极影响，与骨体积/密度的变化无关。这可能有助于解释雷洛昔芬如何减少骨质疏松性骨折，尽管骨量的适度变化。
We have previously documented that raloxifene enhances the mechanical properties of dog vertebrae independent of changes in bone mass, suggesting a positive effect of raloxifene on material-level mechanical properties. The goal of this study was to determine the separate effects of raloxifene on the material- level mechanical properties of trabecular and cortical bone from the femur of beagle dogs. Skeletally mature female beagles (n = 12 per group) were treated daily for 1 yr with oral doses of vehicle or raloxifene (0.50 mg/ kg center dot d). Trabecular bone mechanical properties were measured at the femoral neck using reduced platen compression, a method that allows the trabecular bone to be tested without coring specimens. Cortical bone properties were assessed on prismatic beam specimens machined from the femoral diaphysis using both monotonic and dynamic (cyclic relaxation) fourpoint bending tests. Trabecular bone from raloxifene- treated animals had significantly higher ultimate stress ( + 130%), modulus (+ 89%), and toughness (+ 152%) compared with vehicletreated animals. Cortical bone from raloxifene- treated animals had significantly greater toughness (+ 62%) compared with vehicle, primarily as a function of increased postyield displacement (+ 100%). There was no significant difference between groups in the percentage of stiffness loss during cortical bone cyclic relaxation tests. These results are consistent with previous data from the vertebrae of these same animals, showing raloxifene has positive effects on biomechanical properties independent of changes in bone volume/density. This may help explain how raloxifene reduces osteoporotic fractures despite modest changes in bone mass.