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Abstract：
Histomorphometry of rodent metaphyseal trabecular bone, by histology or microCT, is generally restricted to the mature secondary spongiosa, excluding the primary spongiosa nearest the growth plate by imposing an \'offset\'. This analyses the bulk static properties of a defined segment of secondary spongiosa, usually regardless of proximity to the growth plate. Here we assess the value of trabecular morphometry that is spatially resolved according to the distance \'downstream\' of-and thus time since formation at-the growth plate. Pursuant to this, we also investigate the validity of including mixed primary-secondary spongiosal trabecular bone, extending the analysed volume \'upstream\' by reducing the offset. Both the addition of spatiotemporal resolution and the extension of the analysed volume have potential to enhance the sensitivity of detection of trabecular changes and to resolve changes occurring at different times and locations.
Two experimental mouse studies of trabecular bone are used as examples of different factors influencing metaphyseal trabecular bone: (1) ovariectomy (OVX) and pharmacological prevention of osteopenia and (2) limb disuse induced by sciatic neurectomy (SN). In a third study into offset rescaling, we also examine the relationship between age, tibia length, and primary spongiosal thickness.
Bone changes induced by either OVX or SN that were early or weak and marginal were more pronounced in the mixed primary-secondary upstream spongiosal region than in the downstream secondary spongiosa. A spatially resolved evaluation of the entire trabecular region found that significant differences between experimental and control bones remained undiminished either right up to or to within 100 μm from the growth plate. Intriguingly, our data revealed a remarkably linear downstream profile for fractal dimension in trabecular bone, arguing for an underlying homogeneity of the (re)modelling process throughout the entire metaphysis and against strict anatomical categorization into primary and secondary spongiosal regions. Finally, we find that a correlation between tibia length and primary spongiosal depth is well conserved except in very early and late life.
These data indicate that the spatially resolved analysis of metaphyseal trabecular bone at different distances from the growth plate and/or times since formation adds a valuable dimension to histomorphometric analysis. They also question any rationale for rejecting primary spongiosal bone, in principle, from metaphyseal trabecular morphometry.
Two experimental mouse studies of trabecular bone are used as examples of different factors influencing metaphyseal trabecular bone: (1) ovariectomy (OVX) and pharmacological prevention of osteopenia and (2) limb disuse induced by sciatic neurectomy (SN). In a third study into offset rescaling, we also examine the relationship between age, tibia length, and primary spongiosal thickness.
Bone changes induced by either OVX or SN that were early or weak and marginal were more pronounced in the mixed primary-secondary upstream spongiosal region than in the downstream secondary spongiosa. A spatially resolved evaluation of the entire trabecular region found that significant differences between experimental and control bones remained undiminished either right up to or to within 100 μm from the growth plate. Intriguingly, our data revealed a remarkably linear downstream profile for fractal dimension in trabecular bone, arguing for an underlying homogeneity of the (re)modelling process throughout the entire metaphysis and against strict anatomical categorization into primary and secondary spongiosal regions. Finally, we find that a correlation between tibia length and primary spongiosal depth is well conserved except in very early and late life.
These data indicate that the spatially resolved analysis of metaphyseal trabecular bone at different distances from the growth plate and/or times since formation adds a valuable dimension to histomorphometric analysis. They also question any rationale for rejecting primary spongiosal bone, in principle, from metaphyseal trabecular morphometry.
摘要：
■啮齿动物干phy端小梁骨的组织形态计量学，通过组织学或显微CT，通常仅限于成熟的次生海绵体，通过施加\'偏移\'排除最接近生长板的主要海绵体。这分析了定义的次生海绵体段的整体静态特性，通常与生长板的接近程度无关。在这里，我们评估了小梁形态测量的值，该测量值是根据生长板形成后的距离“下游”和时间进行空间分辨的。据此,我们还研究了包括混合原发-次发海绵状骨小梁骨的有效性，通过减少偏移量来扩展分析卷的“上游”。时空分辨率的增加和分析体积的扩展都有可能增强检测小梁变化的灵敏度，并解决在不同时间和位置发生的变化。
■两项小梁骨的实验小鼠研究被用作影响干phy端小梁骨的不同因素的例子：（1）卵巢切除术（OVX）和药物预防骨质减少和（2）由坐骨神经切除术（SN）引起的肢体废用。在关于偏移重新缩放的第三项研究中，我们还研究了年龄之间的关系，胫骨长度,和主要的海绵体厚度。
■由OVX或SN引起的早期或弱和边缘的骨变化在混合的原发-次发上游海绵状区域比在下游次发海绵状区域更为明显。对整个小梁区域的空间分辨评估发现，实验骨和对照骨之间的显着差异在距生长板100μm或100μm以内都没有减少。有趣的是，我们的数据揭示了小梁骨中分形维数的线性下游分布，主张在整个干phy端（重新）建模过程中具有潜在的同质性，并反对将其严格解剖分类为主要和次要海绵状区域。最后,我们发现，胫骨长度和主要海绵体深度之间的相关性非常保守，除了在早期和晚期。
■这些数据表明，在距生长板和/或形成以来的时间不同的距离下，对干phy端小梁骨的空间分辨分析为组织形态计量学分析增加了有价值的尺寸。他们还质疑拒绝初级海绵状骨的任何理由，原则上,干phy端小梁形态测量。
■两项小梁骨的实验小鼠研究被用作影响干phy端小梁骨的不同因素的例子：（1）卵巢切除术（OVX）和药物预防骨质减少和（2）由坐骨神经切除术（SN）引起的肢体废用。在关于偏移重新缩放的第三项研究中，我们还研究了年龄之间的关系，胫骨长度,和主要的海绵体厚度。
■由OVX或SN引起的早期或弱和边缘的骨变化在混合的原发-次发上游海绵状区域比在下游次发海绵状区域更为明显。对整个小梁区域的空间分辨评估发现，实验骨和对照骨之间的显着差异在距生长板100μm或100μm以内都没有减少。有趣的是，我们的数据揭示了小梁骨中分形维数的线性下游分布，主张在整个干phy端（重新）建模过程中具有潜在的同质性，并反对将其严格解剖分类为主要和次要海绵状区域。最后,我们发现，胫骨长度和主要海绵体深度之间的相关性非常保守，除了在早期和晚期。
■这些数据表明，在距生长板和/或形成以来的时间不同的距离下，对干phy端小梁骨的空间分辨分析为组织形态计量学分析增加了有价值的尺寸。他们还质疑拒绝初级海绵状骨的任何理由，原则上,干phy端小梁形态测量。
