TISSUE STRAIN MAGNITUDE EFFECTS ON BONE INGROWTH

描述（改编自申请人的摘要）：本申请 提出了解决次优固定问题的研究， 多孔涂层植入物由于骨长入不良。 两个具体目标是 介绍了 首先是确定不同的初始界面 菌株产生不同量的骨向内生长。 二是 确定界面组织是否适应限制应变范围 200至2500微应变，如针对皮质骨提出的。 的 最近发展的均匀化取样程序， 申请人提供了估计组织应变的能力 第一次真实地 该技术结合了 独特的，完善的犬模型系统，允许控制 施加于犬暴露骨小梁的植入物载荷 股骨远端将用于测试界面组织的假设 适应于将应变限制在稳态范围内。 三种不同 动物组将受到三种不同程度的 载荷，范围从0到8磅。 动物将在 术后6个月，将获得骨芯。 I型亲- 胶原和破骨细胞再吸收将在实验中测量 肢体并与对侧肢体进行比较，以确定 骨骼处于平衡状态。 背散射扫描电子 显微镜（SEM）将被用来构建一个三维数字化图像的 在每个台板区域中向内生长。 微型计算机断层扫描（micro-CT） 将用于量化骨结构变化。 图片来自both 利用SEM和micro-CT建立三维显微结构有限元模型 种植体组织界面和周围骨的单元模型。 将使用均质化取样估计组织水平菌株 程序，并用于测试有关组织适应性的假设。 如果骨小梁组织确实适应在体内平衡的环境中存在 应变范围，这将为设计多孔涂层 可以实现更好的骨长入固定的植入物界面。

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.