AUGMENTATION OF TRABECULAR BONE BY LOW MAGNITUDE STRAIN

该实验室的初步工作表明， 强度（<30微应变）的机械信号可以是成骨的， 以高频率（5至50 Hz）施加。如此高的频率低 大小应变包括骨应变的重要组成部分 历史，这表明这些机械事件可能代表了一个 骨形态的重要决定因素。我们假设， 增加高频负荷，非侵入性地引入 通过振动骨骼，将刺激骨质增加， 牺牲骨质考虑到这些应变水平远低于 （<1/100）那些可能对组织造成损害的，我们认为这些 信号作为骨质疏松的机械预防方法具有巨大潜力。 使用哺乳成熟绵羊，随机、部分5x 4x 3析因 实验设计，评估频率（7.5、15、30、60或120 Hz）， 持续时间（5、10、20或40 min）和强度（0.1、0.2或0.4 g）将 用于确定非侵入性机械装置的功效， 增加胫骨和股骨的骨小梁一系列体内和 将使用离体方案来量化这12种细胞的能力。 个月的机械干预，以影响骨量和形态。 双能X射线吸收法将确定密度的变化， 时间函数，动态和静态组织形态计量学将量化 反应的部位特异性、质量和程度，以及机械 测试将用于确定这种处理是否影响强度 和骨骼治疗区域的硬度。最后， 成骨机械信号将用于确定骨密度， 强度和刚度可以在骨质减少的骨骼中恢复。 这些实验可能会产生新的见解的机制， 机械因素控制骨形态，以及导致一种新的 治疗骨质疏松症。

Preliminary work in this laboratory has demonstrated that extremely low magnitude (<30 Microstrain) mechanical signals can be osteogenic if applied at a high frequency (5 to 50 Hz). Such high frequency low magnitude strains comprise an important constituent of a bone's strain history, suggesting that these mechanical events could represent a significant determinant of bone morphology. We hypothesize that small increases in high frequency loading, introduced non-invasively into the skeleton via vibration, will stimulate an increase in bone mass without sacrificing bone quality. Considering these strain levels are well below (<1/100th) those which may cause damage to the tissue, we believe these signals hold great potential as a mechanical prophylaxis for osteopenia. Using skeletally mature sheep, a randomized, partial 5x4x3 factorial experimental design, evaluating frequency (7.5, 15, 30, 60 or 120 Hz), duration (5, 10, 20 or 40 min), and intensity (0.1, 0.2 or 0.4g) will be used to determine the efficacy of a non-invasive mechanical device to augment the trabeculae of the tibia and femur. A series of in vivo and ex vivo protocols will be used to quantify the ability of this twelve month mechanical intervention to affect both bone mass and morphology. Dual energy x-ray absorptiometry will determine changes in density as a function of time, dynamic and static histomorphometry will quantify the site-specificity, quality, and extent of the response, and mechanical testing will be used to determine if this treatment influences strength and stiffness of the treated regions of the skeleton. Finally, the most osteogenic mechanical signals will be used to determine if bone density, strength, and stiffness can be recovered in the osteopenic skeleton. These experiments may yield new insights into the mechanisms by which mechanical factors control bone morphology, as well as lead to a novel treatment for osteoporosis.