Rosenthal Andrew H, Buchman Steven R
Section of Plastic and Reconstructive Surgery, Department of Surgery, University of Michigan, Ann Arbor 48109-0340, USA.
Plast Reconstr Surg. 2003 Sep;112(3):802-11. doi: 10.1097/01.PRS.0000069713.62687.F5.
Although the clinical use of inlay bone grafts is widespread in craniofacial surgery, the dynamics of inlay bone grafting to the craniofacial skeleton have never been well characterized. Previous work demonstrated that volume maintenance of bone grafts in the onlay position is a consequence of their microarchitectural features, rather than their embryological origins. The purpose of this study was to investigate whether the properties determining the volume maintenance of bone grafts in the onlay position in the craniofacial skeleton could be extended to bone grafts in the inlay position. It was hypothesized that volume maintenance of an inlay bone graft could be better explained on the basis of the microarchitectural features of the graft (cortical versus cancellous composition), rather than its embryological origin (membranous versus endochondral), and that the primary determinant of bone graft behavior is the interaction between the microarchitectural features of the bone graft and the local mechanical environment in which the bone graft is placed. Cortical and cancellous bone grafts were harvested from the iliac crest (endochondral origin) of 25 New Zealand white rabbits, and cortical bone was harvested from the mandible (membranous origin) of each rabbit. Four 7-mm trephine holes were made in the cranium of each rabbit, posterior to the coronal suture. Each defect was filled with endochondral cortical bone, endochondral cancellous bone, or membranous cortical bone or was left as an ungrafted control specimen. Animals were killed at 3, 8, or 16 weeks. Crania were subjected to micro-computed tomographic and histological assessments. Micro-computed tomographic analysis demonstrated significant increases in actual bone volume from time 0 to the time of death for all types of grafts. Cortical bone demonstrated significant increases in space-occupying volume at all time points. By 16 weeks, no statistically significant difference in either the actual bone volume or the space-occupying volume according to graft type could be detected. There was no resorption of the inlay bone grafts; in fact, all bone types exhibited increased volume. Cancellous bone demonstrated the greatest capacity to increase actual bone volume. All bone graft types seemed to reach a steady-state bone volume, as if controlled by a local regulator. The regulator is likely the local mechanical environment in which the grafts were placed, as corroborated by the findings that the bone grafts seemed to recapitulate the characteristics of the bone in which they were placed, rather than maintaining their native characteristics.
尽管嵌体骨移植在颅面外科手术中的临床应用广泛，但嵌体骨移植到颅面骨骼的动态过程从未得到很好的描述。先前的研究表明，骨移植在覆盖位置的体积维持是其微观结构特征的结果，而非胚胎学起源。本研究的目的是调查决定骨移植在颅面骨骼覆盖位置体积维持的特性是否可扩展到嵌体位置的骨移植。研究假设，嵌体骨移植的体积维持基于移植骨的微观结构特征（皮质骨与松质骨组成）能得到更好解释，而非其胚胎学起源（膜内成骨与软骨内成骨），并且骨移植行为的主要决定因素是骨移植的微观结构特征与骨移植所处局部力学环境之间的相互作用。从25只新西兰白兔的髂嵴（软骨内成骨起源）获取皮质骨和松质骨移植骨，并从每只兔子的下颌骨（膜内成骨起源）获取皮质骨。在每只兔子冠状缝后方的颅骨上制作4个7毫米的环钻孔。每个缺损处填充软骨内皮质骨、软骨内松质骨或膜内皮质骨，或留作未移植的对照标本。在3周、8周或16周时处死动物。对颅骨进行显微计算机断层扫描和组织学评估。显微计算机断层扫描分析表明，所有类型的移植骨从时间0到处死时实际骨体积均显著增加。皮质骨在所有时间点的占位体积均显著增加。到16周时，根据移植骨类型，在实际骨体积或占位体积方面均未检测到统计学上的显著差异。嵌体骨移植没有吸收；事实上，所有骨类型的体积均增加。松质骨增加实际骨体积的能力最强。所有骨移植类型似乎都达到了稳定的骨体积，仿佛受局部调节因子控制。该调节因子可能是移植骨所处的局部力学环境，这一发现得到了证实，即骨移植似乎重现了其所处骨的特征，而非保持其固有特征。
