Structural changes with aging in cortical bone of the human tibia.
Structural changes with aging in cortical bone of the human tibia.
复制标题
人类胫骨皮质骨随衰老的结构变化。
作者：
C. Nyssen;P. Duchesne;A. Dhem
结构改变被认为在与年龄相关的骨质量和强度改变中发挥着重要作用。衰老致密骨的特征在于各方面的异质性增加，包括大量低矿化骨以及具有高矿化板层或具有凹口哈弗管壁的骨以及双区骨的存在。后三种类型的骨与哈弗重塑所涉及的结构不同。在本研究中，将 7 名年轻男性（18-39 岁）、14 名老年男性（50-92 岁）和 15 名老年女性（57-96 岁）的中轴胫骨块嵌入甲基丙烯酸甲酯中，以便对未脱钙切片进行显微放射学和组织形态学分析。老年男性的皮质内孔隙率高于年轻人，哈弗结构的数量也高于年轻人，哈弗神经管的直径也较小。老年女性也表现出同样的趋势，皮质孔隙度仍高于男性。具有高矿化板层的骨、具有缺口管的骨和双区骨似乎构成了整个哈弗人群的大亚群，即使在成年早期也是如此。其中，只有管壁有缺口的骨块出现频率随着年龄的增长而增加。这三种类型比典型的哈弗重构中涉及的结构要多得多。它们的频率之间的相关性以及它们显着的地形关联证实了这样的假设，即超矿化的薄片可能由于其过度的脆性而崩溃，从而产生具有凹口壁的哈弗运河。这些扩大的根管可以通过骨并置来重新填充，并产生双区骨。这三种类型的骨可以构成渐进发生的骨崩解和修复的一种机制的不同步骤，这可能有助于改变骨质量并增加皮质内孔隙率。
Structural modifications are considered to play a significant role in the age-related alterations of bone quality and strength. Senescent compact bone is characterized by an increasing heterogeneity of aspects, including high numbers of lowly mineralized osteons as well as the presence of osteons with hypermineralized lamellae or with a notched haversian canal wall, and of double-zone osteons. These latter three types of osteons are different from the structures involved in the haversian remodeling. In the present study, blocks of midshaft tibia from 7 young men (18-39 years), 14 aged men (50-92 years) and 15 aged women (57-96 years) were embedded in methyl methacrylate in order to perform microradiographic and histomorphometric analysis of undecalcified sections. The intracortical porosity was higher in the aged men than in the young ones, as were the numbers of haversian structures and, to a lesser extent, the diameters of the haversian canals. The aged women showed the same tendency, with cortical porosity still higher than in the men. The osteons with hypermineralized lamellae, those with a notched canal and the double-zone osteons appear to constitute large subgroups of the total haversian population, even in the early adult life. Among them, only the osteons with a notched canal wall increased in frequency with age. The 3 types are much more numerous than the structures involved in the typical haversian remodeling. The correlations between their frequencies as well as their significant topographic association corroborates the hypothesis that the hypermineralized lamellae may crumble down because of their excessive brittleness, giving rise to the haversian canals with notched walls. These enlarged canals could be refilled by bone apposition and result in the double-zone osteons. The 3 types of osteons could constitute different steps of one mechanism of bone desintegration and repair occurring very progressively, which might contribute to modify the bone quality and to increase the intracortical porosity.