Dipartimento di Morfologia Umana, Università dell'Insubria, Varese, Italy.
Anat Rec (Hoboken). 2011 Feb;294(2):193-8. doi: 10.1002/ar.21309. Epub 2010 Dec 3.
The frequency, structure, mode of formation and significance of sealed osteons remain unsettled. Sealed osteons have been reported as an unusual finding in the cortical bone of experimental animals: we extended the observation to human cortical bone studied with SEM. Tibial bone specimens from three patients who sustained a traumatic below-the-knee amputation were used in the study. The observed total mean density of osteons was 19.25/mm(2) and the percentage of sealed and partially sealed osteons was 4.2% and 1.7% respectively. The material sealing the central canal showed an X-ray microanalysis spectrum with the same Ca/P ratio as the peripheral lamellae and a lower carbon signal. The morphology suggested a reactivation of bone apposition triggered by exclusion of the occluded canal from blood flow rather than a physiological evolution of the closing process of secondary osteons. This presupposes collapse and degeneration of the central vessel before the osteoblasts resting on the inner surface of the canal could start to lay down new bone matrix. This explanation is consistent with a dynamic model of intracortical blood flow.
封闭骨单位的频率、结构、形成模式及其意义仍未确定。封闭骨单位在实验动物皮质骨中被报道为一种不寻常的发现：我们将观察扩展到使用 SEM 研究的人类皮质骨。本研究使用了 3 名因创伤性膝下截肢而截肢的患者的胫骨骨标本。观察到的平均骨单位总密度为 19.25/mm²，封闭和部分封闭骨单位的百分比分别为 4.2%和 1.7%。封闭中央管的材料显示出与周围薄板相同的 Ca/P 比值和较低的碳信号的 X 射线微分析谱。形态学提示，闭塞管腔从血流中排除触发了骨沉积的重新激活，而不是继发性骨单位闭合过程的生理演变。这意味着中央血管在休息在管腔内表面的成骨细胞开始沉积新的骨基质之前发生了塌陷和退化。这种解释与皮质内血流的动态模型一致。
