BIOMECHANICS OF DISTAL RADIUS BONE MINERAL

绝经后骨质疏松症是一个全国性的健康问题。 接近危机比例，约有130万人骨折 据估计，每年的成本接近40亿美元。趁有机会 越来越多的证据表明，某些治疗措施可以帮助 延缓骨质流失，从而减少骨折发生率，有些 治疗方式本身与显著的 风险和病人成本。它变得越来越重要， 因此，为了识别有骨折风险的患者，以便 可以进行适当的治疗。被普遍接受的 骨质疏松症筛查标准保持单光子 骨密度扫描法测定骨矿物质含量 (BMC)。然而，尽管它广泛存在 临床应用中，BMC测量反映了联合影响 骨密度和横断面几何形状的变化。我们有 如前所述，通常应用归一化过程 (除以骨骼宽度)并不能有效消除这一点 关键的和无法解释的差异来源。因为生物力学 性能随骨骼几何形状的幂函数而变化， 这可能很好地解释了为什么 桡骨光子吸收法在骨折危险性评估中的应用 其他骨骼部位。该试点项目的目的是扩展 可用的光子吸收扫描技术，允许 几何效应和密度效应的分离。10双 新鲜冷冻的女性身体前臂，我们将： 1)测定BMC和BMC/W在标准临床和两个 增加辐射站点；2)开发和实施新的 吸光度测定程序和数据简化算法 截面几何和密度测量的分离 变量；3)在物理上将每对的一个半径 扫描部位并确定皮质和小梁区 分数，孔隙率加权的主面惯性矩， 以及皮质骨的表观密度和力学性能 和骨小梁；4)进行氦气体外失效试验 对侧前臂在多轴载荷下的模拟 Colle骨折；以及5)比较判别性和预测性 现有的和实验中的吸光度测量能力 针对；a)横截面的直接测量 几何学；b)骨密度和材料特性；以及c)体外 断裂载荷。需要检验的假设是，提取 几何信息的使用将显著提高 该技术的生物力学预测能力，因此 作为新的和更准确的筛查的基础 骨质疏松症的诊断和治疗评价程序。

Post-menopausal osteoporosis is a national health problem of nearly crisis proportions with approximately 1.3 million fractures and estimated annual costs of close to $4 billion. While there is growing evidence that certain therapeutic measures can help retard bone loss and thus reduce fracture incidence, some treatment modalities are themselves associated with significant risks and patient costs. It becomes increasingly important, therefore, to identify those patients at risk of fracture so that appropriate therapy can be instituted. The universally accepted standard for osteoporosis screening remains single photon absorptiometric scanning to determine bone mineral content (BMC) of the distal radius. However, despite its widespread clinical use, BMC measurements reflect the combined influences of changes in bone density and cross-sectional geometry. We have shown previously that commonly applied normalization procedures (dividing by bone width) does not effectively eliminate this critical and unexplained source of variance. Since biomechanical performance varies as power law functions of the bone geometry, this may well explain the relatively poor predictive capability of photon absorptiometry of the radius in assessing fracture risk at other skeletal sites. The intent of this Pilot Project is to extend available photon absorptiometric scanning technology to allow a separation of geometric and densitometric effects. For 10 pairs of fresh-frozen cadaveric forearms from human females, we will: 1) determine BMC and BMC/W at standard clinical and two additional radial sites; 2) develop and implement new absorptiometric procedures and data reduction algorithms for the separation of cross-sectional geometric and densitometric variables; 3) physically section one radius of each pair at the scanned sites and determine cortical and trabecular areal fractions, porosity-weighted principal areal moments of inertia, and the apparent densities and mechanical properties of cortical and trabecular bone; 4) conduct in vitro failure tests of he contralateral forearm under multi-axial loading simulating a Colle's fracture; and 5) compare the discriminatory and predictive capabilities of available and experimental absorptiometric techniques against; a) direct measures of cross sectional geometry; b) bone density and material properties; and c) in-vitro fracture load. The hypothesis to be tested is that the extraction of geometric information will significantly improve the biomechanical predictive capabilities of this technique and thus serve as the basis for new and more accurate screening procedures for diagnosis and treatment evaluation in osteoporosis.