Orthopeadic Research Laboratory, Department of Orthopaedic Surgery & Traumatology, Odense University Hospital, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.
Department of Clinical Cell Biology, Vejle Hospital/Lillebaelt Hospital, Institute of Regional Health Research, University of Southern Denmark, Vejle, Denmark.
J Bone Miner Res. 2018 Apr;33(4):606-620. doi: 10.1002/jbmr.3354. Epub 2018 Jan 4.
Intracortical bone remodeling normally ensures maintenance of the cortical bone matrix and strength, but during aging, this remodeling generates excessive porosity. The mechanism behind the age-induced cortical porosity is poorly understood and addressed in the present study. This study consists of a histomorphometric analysis of sections of iliac bone specimens from 35 women (age 16-78 years). First, the study shows that the age-induced cortical porosity reflects an increased pore size rather than an increased pore density. Second, it establishes a novel histomorphometric classification of the pores, which is based on the characteristics of the remodeling sites to which each pore is associated. It takes into consideration (i) the stage of the remodeling event at the level where the pore is sectioned, (ii) whether the event corresponds with the generation of a new pore through penetrative tunneling (type 1 pores) or with remodeling of an existing pore (type 2 pores), and (iii) in the latter case, whether or not the new remodeling event leads to the coalescence of pores. Of note, the advantage of this classification is to relate porosity with its generation mechanism. Third, it demonstrates that aging and porosity are correlated with: a shift from type 1 to type 2 pores, reflecting that the remodeling of existing pores is higher; an accumulation of eroded type 2 pores, reflecting an extended resorption-reversal phase; and a coalescence of these eroded type 2 pores into enlarged coalescing type 2 cavities. Collectively, this study supports the notion, that age-related increase in cortical porosity is the result of intracortical remodeling sites upon existing pores, with an extended reversal-resorption phase (eroded type 2 pores) that may likely result in a delayed or absent initiation of the subsequent bone formation. © 2017 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.
皮质骨内骨重塑通常可确保皮质骨基质和强度的维持，但在衰老过程中，这种重塑会产生过多的多孔性。目前的研究中，对年龄引起的皮质多孔性的机制知之甚少。本研究包括对 35 名女性（年龄 16-78 岁）的髂骨标本切片进行组织形态计量学分析。首先，该研究表明，年龄引起的皮质多孔性反映了孔径的增加，而不是孔密度的增加。其次，它建立了一种新的基于重塑部位特征的孔隙分类方法，该方法考虑到了每个孔隙所关联的重塑部位的特征。它考虑到了（i）在孔隙所在的水平上，重塑事件所处的阶段，（ii）该事件是否对应于通过穿透性隧道（1 型孔隙）产生新孔隙，或者对应于现有孔隙的重塑（2 型孔隙），以及（iii）在后一种情况下，新的重塑事件是否导致孔隙融合。值得注意的是，这种分类的优点是将孔隙率与其产生机制联系起来。第三，它表明，衰老和多孔性与以下因素相关：从 1 型向 2 型孔隙的转变，反映了现有孔隙的重塑增加；侵蚀性 2 型孔隙的积累，反映了吸收-再吸收阶段的延长；以及这些侵蚀性 2 型孔隙融合成较大的融合性 2 型腔。总的来说，这项研究支持这样一种观点，即皮质多孔性的年龄相关性增加是由于现有孔隙上的皮质内重塑部位所致，延长的再吸收-逆转阶段（侵蚀性 2 型孔隙）可能导致随后的骨形成延迟或缺失。© 2017 作者。由 Wiley 期刊公司出版的《骨与矿物研究杂志》
