Porous Nitinol for Load Bearing Implants Using Rapid Prototyping

该奖项的研究目标是应用激光工程净成形（透镜（TM）），一种基于快速原型的先进制造技术，以创建镍钛诺的多孔结构。将测量不同孔隙率的镍钛合金结构的物理、机械和生物学特性。在承重植入物中使用多孔材料可以减少由于多孔性引起的刚度失配，并解决长期存在的问题，如应力遮挡。由于骨组织从表面到内部向内生长成相互连接的多孔结构，设计的多孔结构还将实现稳定的长期生物固定。镍钛诺是一种形状记忆合金，显示高达8%的可恢复应变，类似于观察到约1%的可恢复应变的骨。镍钛合金和骨之间变形行为的这种相似性有助于在体内加载-卸载条件下承重植入物的相同性能，确保良好的生物力学相容性。镍钛诺也是一种生物相容性材料，目前用于多种生物医学器械。该方法是使用灵活的透镜（TM）参数来制造多孔镍钛合金植入物与设计的宏观和微观多孔结构，以实现所需的性能。然后将建立透镜（TM）制造的镍钛诺的机械和生物性能的工艺-性能关系。如果成功的话，该计划的结果将提供设计和制造简单和复杂形状植入物的灵活性，这种植入物具有新型形状记忆合金镍钛诺，可以匹配骨的机械性能。新型多孔植入物可能使承重植入物的使用寿命增加一倍或三倍。作为一种计算机辅助的、基于设计的过程，透镜（TM）也可用于根据计算机断层扫描和磁共振成像数据制造患者特定的植入物。该项目还将教育和培训机械工程、材料科学和工程以及生物工程方面的研究生和本科生。

The research objective of this award is to apply Laser Engineered Net Shaping (LENS(TM)), a rapid prototyping based advanced manufacturing technology, to create porous structures of nitinol. The physical, mechanical and biological properties of nitinol structures of varying porosity will be measured. Use of porous materials in load bearing implants can reduce the stiffness mismatches due to porosity and solve long-standing problems like stress shielding. Designed porosity will also achieve stable long-term biological fixation due to bone-tissue in-growth into interconnected porosity from the surface to the inside. Nitinol is a shape memory alloy that shows up to 8 percent recoverable strain, similar to bone in which about 1 percent recoverable strain is observed. This similarity in the deformation behavior between Nitinol and bone contribute to identical performance of load bearing implants under loading-unloading conditions in the body ensuring excellent biomechanical compatibility. Nitinol is also a biocompatible material and currently in use in several biomedical devices. The approach is to use flexible LENS(TM) parameters to fabricate porous nitinol implants with designed macro and micro porous structures to achieve desired performance. Process-property relationships, for both mechanical and biological properties, for LENS(TM) fabricated nitinol will then be established.If successful, results from this program will offer design and manufacturing flexibility of simple and complex shaped implants with novel shape memory alloy, nitinol, that can match mechanical properties of bone. Novel porous implants can potentially double or triple the lifetime of load bearing implants. Being a computer-aided, design-based process, LENS(TM) can also be used to fabricate patient-specific implants from computed tomography and magnetic resonance imaging data. The project will also educate and train graduate and undergraduate students in mechanical engineering, materials science and engineering and bioengineering.