TISSUE STRAIN MAGNITUDE EFFECTS ON BONE INGROWTH

描述(改编自申请人的摘要)：本申请 提出了解决非最佳固定的问题的研究 多孔性涂层植入物是由于骨向内生长不良。两个具体目标是 描述。第一个是确定不同的初始接口是否 菌株会产生不同数量的骨长入。第二个是 确定界面组织是否适应将应变限制在 皮质骨的微应变为200到2500微应变。这个 均质化取样程序的最新进展 申请人提供评估组织应变的能力 现实地说，这是第一次。这项技术，与一种 独特的，完善的犬类模型系统，允许控制 对暴露的犬骨松质骨施加植入载荷 股骨远端，将被用来检验界面组织的假设 适应将应变限制在动态平衡范围内。三种不同的 一组动物将受到三种不同程度的 装载，从0磅到8磅不等。这些动物将被牺牲在 术后6个月取骨芯。第一类职业- 将在实验中测量胶原蛋白和破骨细胞的吸收。 并与对侧肢体进行比较，以确定 骨骼就是保持平衡。背散射扫描电子 显微镜(扫描电子显微镜)将被用来构建一个三维数字化图像 在每个压板区域内长入。微型计算机断层扫描(Micro-CT) 将被用于量化骨骼结构的变化。来自这两个地方的图像 利用扫描电子显微镜和显微CT技术构建三维微结构有限元模型 种植体组织界面和周围骨骼的单元模型。 组织水平的菌株将使用均质化抽样进行估计 程序，并用于检验有关组织适应的假说。 如果骨小梁组织确实适应在动态平衡中存在 应变范围，这将为设计多孔涂层提供标准 可实现更好的骨向内固定的种植界面。

DESCRIPTION (adapted from the applicant's Abstract): This application proposes studies which address the problem of suboptimal fixation of porous coated implants due to poor bone ingrowth. Two specific aims are described. The first is to determine if different initial interface strains produce different amounts of bone ingrowth. The second is to determine if interface tissue adapts to limit strains within a range of 200 to 2500 microstrain as has been proposed for cortical bone. The recent development of an homogenization sampling procedure by the applicant provides the capability for estimating tissue strains realistically for the first time. The technique, combined with a unique, well-established canine model system which allows controlled implant loads to be applied to exposed trabecular bone of the canine distal femur, will be used to test the hypothesis that interface tissue adapts to limit strain within a homeostatic range. Three different groups of animals will be subjected to three different magnitudes of loading, ranging from 0 to 8 pounds. The animals will be sacrificed at 6 months post surgery and bone cores will be obtained. Type I pro- collagen and osteoclast resorption will be measured in the experimental limb and compared to the contralateral limb to determine how close the bone is to being at equilibrium. Backscattered scanning electron microscopy (SEM) will be used to construct a 3-D digitized image of the ingrowth in each platen region. Micro-computed tomography (micro-CT) will be used to quantify bone architectural changes. Images from both SEM and micro-CT will be used to construct 3-D microstructural finite element models of the implant tissue interface and the surrounding bone. Tissue level strains will be estimated using the homogenization sampling procedure and used to test the hypotheses concerning tissue adaptation. If trabecular bone tissue does adapt to exist within a homeostatic strain range, this would provide criteria for designing porous coated implant interfaces that may achieve better bone ingrowth fixation.