Department of Mechanical Engineering, the University of Michigan, Ann Arbor, MI 48109-2110, USA.
J Biomech. 2012 Aug 31;45(13):2241-7. doi: 10.1016/j.jbiomech.2012.06.011. Epub 2012 Jul 11.
The future development of bio-integrated devices will improve the functionality of robotic prosthetic limbs. A critical step in the advancement of bio-integrated prostheses will be establishing long-term, secure fixation to the remnant bone. To overcome limitations associated with contemporary bone-anchored prosthetic limbs, we established a paradigm for developing and fabricating novel orthopedic implants undergoing specified loading. A topology optimization scheme was utilized to generate optimal implant macrostructures that minimize deformations near the bone-implant interface. Variations in implant characteristics and interfacial connectivity were investigated to examine how these variables influence the layout of the optimized implant. For enhanced tissue integration, the optimally designed macroscopic geometry of a titanium (Ti)-alloy implant was further modified by introducing optimized microstructures. The complex geometries of selected implants were successfully fabricated using selective laser sintering (SLS) technology. Fabrication accuracy was assessed by comparing volumes and cross-sectional areas of fabricated implants to CAD data. The error of fabricated volume to CAD design volume was less than 8% and differences in cross sectional areas between SEM images of fabricated implants and corresponding cross sections from CAD design were on average less than 9%. We have demonstrated that this computational design method, combined with solid freeform fabrication techniques, provides a versatile way to develop novel orthopedic implants.
生物集成设备的未来发展将提高机器人假肢的功能。生物集成假肢的一个关键步骤是实现与残余骨的长期、安全固定。为了克服与当代骨锚定假肢相关的局限性，我们建立了一个用于开发和制造经过特定负载的新型骨科植入物的范例。利用拓扑优化方案生成可使骨-植入物界面附近变形最小化的优化植入物宏观结构。研究了植入物特性和界面连接性的变化，以研究这些变量如何影响优化植入物的布局。为了增强组织整合，通过引入优化的微观结构，进一步修改了钛 (Ti) 合金植入物的最佳设计宏观几何形状。使用选择性激光烧结 (SLS) 技术成功制造了选定植入物的复杂几何形状。通过将制造的植入物的体积和横截面积与 CAD 数据进行比较来评估制造精度。制造体积与 CAD 设计体积的误差小于 8%，并且制造植入物的 SEM 图像的横截面积与 CAD 设计的相应横截面积之间的差异平均小于 9%。我们已经证明，这种计算设计方法与自由形态制造技术相结合，为开发新型骨科植入物提供了一种通用方法。
