FEASIBILITY STUDY--BONE DYNAMIC STRENGTH WITH IMPROVED CEMEMT

每年有超过200,000例关节置换手术。 美国。虽然基本上是成功的，但据报道， 大量长期故障，其中许多涉及 丙烯酸骨水泥和/或界面的破裂 在骨头和水泥之间。已经有人尝试过 通过以下方法去除水泥的一些内部孔隙率来改善水泥 搅拌过程中的离心法。在我们的实验室里， 真空搅拌碗是最近开发出来的，它可以去除 更多的孔隙率，并创造出一种更好的粘结剂 在机械单轴拉伸和压缩强度以及 具有更长的拉伸疲劳寿命。一个重大问题 如果真空搅拌水泥的优越性能仍然存在 其本身将转移到骨水泥/骨界面以产生 增强了机械结合。使用长期、低负荷的循环 通过裂纹扩展产生水泥断裂的测试模式， 有人建议研究更强水泥的可行性。 创造更好的骨水泥/骨结合。 虽然精通高负荷的测定，但在塑性方面 人造牙体和牙体的变形单轴力学性能 医疗材料，首席调查员将不得不 显著改变了他的研究领域，以便学习 复合体低周弹性加载的断裂力学 多组件接口。 研究计划是创造骨水泥/骨界面标本， 高度重视混合技术等变量， 安置率和压力，加上性质和准备 身体松质骨床。然后，让这些标本 界面试验，如搭接剪切、环状剪切、弯曲和破裂 传播。这些将在37摄氏度的生理模拟中完成 液体在准静态和临床上更相关的长时间 术语、低幅度循环动载，以便评估 确定断裂机制的可行性和 增强骨水泥/骨界面的强度。

Over 200,000 total joint replacements are performed yearly in the United States. Although basically succesful, there are reported a significant number of long term failures, many of which involve breakdown of the acrylic bone cement and/or the interface between the bone and the cement. Attempts have been made to improve the cement by removing some of its internal porosity by means of centrifugation during mixing. In our laboratory a partial vacuum mixing bowl has been recently developed which removes even more of the porosity and creates a cement which is superior in mechanical uniaxial tensile and compression strength as well as having much greater tensile fatigue life. A major question remains if the superior properties of the vacuum mixed cement itself will transfer to the cement/bone interface to produce an enhanced mechanical bond. Using long term, low loading cyclic testing modes to produce cement fracture by crack propagation, it is proposed to investigate the feasibility of stronger cements creating better cement/bone bonding. Although well versed in the determination of high load, plastically deforming uniaxial mechanical properties of synthetic dental and medical materials, the principal investigator would have to significantly shift his area of research in order to learn to study the fracture mechanics of low cyclic, elastic loading of complex, multicomponent interfaces. The research plan is to create cement/bone interface specimens, paying great attention to such variables as mixing technique, placement rates and pressures, plus nature and preparation of the cadaveric cancellous bony bed. Then, subject these specimens to interface tests such as lap shear, ring shear, bending and crack propagation. These will be done in 37 C physiologically simulating fluids in both quasi-static and the more clinically relevant long term, low magnitude cyclic dynamic loading in order to evaluate the feasibility of determining the fracture mechanisms and enhancement of the strength of the cement/bone interface.