Pittsburgh, Pa.; and Cleveland, Ohio From the Department of Surgery, Division of Plastic Surgery, the Departments of Oral Biology, Bioengineering, Anthropology, Orthodontics, Orthopaedic Surgery, and Molecular Genetics and Biochemistry, University of Pittsburgh; the Department of Plastic Surgery, Case Western Reserve University School of Medicine; and the Institute of Complex Engineered Systems and Molecular Biosensor and Imaging Center and Departments of Biomedical Engineering, Material Science and Engineering, and Biology, Carnegie Mellon University.
Plast Reconstr Surg. 2010 Jun;125(6):1685-1692. doi: 10.1097/PRS.0b013e3181cb63a3.
There is a clinical need for bone replacement strategies because of the shortfalls endemic to autologous bone grafting, especially in the pediatric patient population. For the past 25 years, the animal model that has been used to test bone replacement strategies has been the calvarial critical-size defect, based on the initial size of the bone defect. This study was undertaken to test the concept of the critical size in several different models. A review of the theoretical and scientific bases for the critical-size defect was also undertaken.
Two different rodent species (including 28 adult mice and six adult rats) were used to assess bone healing by means of two-dimensional radiographic analysis after creating small bone defects using different surgical techniques.
Defects in mice that were smaller than critical-size defects (1.8-mm diameter) were shown to heal a maximum of 50 percent 1 year postoperatively. Small defects (2.3-mm diameter) in the rat skull showed approximately 35 percent healing after 6 weeks. Neither the choice of rodent species nor the maintenance of the dura mater significantly affected calvarial bone healing.
These results suggest that calvarial bone healing is not well described and much more data need to be collected. Also, after a review of the existing literature and a critique of the clinical applicability of the model, it is suggested that the use of the term "critical-size defect" be discontinued.
由于自体骨移植物存在缺陷，特别是在儿科患者群体中，因此需要采用骨替代策略。在过去的 25 年中，基于最初的骨缺损大小，人们一直使用颅骨临界尺寸缺损的动物模型来测试骨替代策略。本研究旨在测试几种不同模型中临界尺寸的概念。还对临界尺寸缺陷的理论和科学基础进行了回顾。
使用两种不同的啮齿动物（包括 28 只成年小鼠和 6 只成年大鼠），通过使用不同的手术技术创建小骨缺损后，通过二维放射分析评估骨愈合情况。
直径小于临界尺寸缺陷（1.8 毫米）的小鼠缺陷在术后 1 年最多可愈合 50%。大鼠颅骨中的小缺陷（2.3 毫米直径）在 6 周后约愈合 35%。选择啮齿动物种类或维持硬脑膜均不会显著影响颅骨骨愈合。
这些结果表明，颅骨骨愈合的描述并不完善，需要收集更多的数据。此外，在对现有文献进行回顾和对模型的临床适用性进行评估后，建议停止使用“临界尺寸缺陷”一词。
