Cohen David J, Cheng Alice, Sahingur Kaan, Clohessy Ryan M, Hopkins Louis B, Boyan Barbara D, Schwartz Zvi
Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, United States of America.
Biomed Mater. 2017 Apr 28;12(2):025021. doi: 10.1088/1748-605X/aa6810.
Long term success of bone-interfacing implants remains a challenge in compromised patients and in areas of low bone quality. While surface roughness at the micro/nanoscale can promote osteogenesis, macro-scale porosity is important for promoting mechanical stability of the implant over time. Currently, machining techniques permit pores to be placed throughout the implant, but the pores are generally uniform in dimension. The advent of laser sintering provides a way to design and manufacture implants with specific porosity and variable dimensions at high resolution. This approach enables production of metal implants that mimic complex geometries found in biology. In this study, we used a rabbit femur model to compare osseointegration of laser sintered solid and porous implants. Ti-6Al-4V implants were laser sintered in a clinically relevant size and shape. One set of implants had a novel porosity based on human trabecular bone; both sets had grit-blasted/acid-etched surfaces. After characterization, implants were inserted transaxially into rabbit femora; mechanical testing, micro-computed tomography (microCT) and histomorphometry were conducted 10 weeks post-operatively. There were no differences in pull-out strength or bone-to-implant contact. However, both microCT and histomorphometry showed significantly higher new bone volume for porous compared to solid implants. Bone growth was observed into porous implant pores, especially near apical portions of the implant interfacing with cortical bone. These results show that laser sintered Ti-6Al-4V implants with micro/nanoscale surface roughness and trabecular bone-inspired porosity promote bone growth and may be used as a superior alternative to solid implants for bone-interfacing implants.
对于身体状况不佳的患者以及骨质量较低的区域，骨界面植入物的长期成功仍然是一项挑战。虽然微观/纳米尺度的表面粗糙度可以促进骨生成，但宏观尺度的孔隙率对于随着时间推移提高植入物的机械稳定性很重要。目前，加工技术允许在整个植入物中设置孔隙，但孔隙尺寸通常是均匀的。激光烧结技术的出现提供了一种以高分辨率设计和制造具有特定孔隙率和可变尺寸的植入物的方法。这种方法能够生产出模仿生物学中复杂几何形状的金属植入物。在本研究中，我们使用兔股骨模型比较激光烧结的实心和多孔植入物的骨整合情况。将Ti-6Al-4V植入物激光烧结成临床相关的尺寸和形状。一组植入物具有基于人松质骨的新型孔隙率；两组植入物都有喷砂/酸蚀表面。经过表征后，将植入物经轴向插入兔股骨；术后10周进行力学测试、微型计算机断层扫描（microCT）和组织形态计量学分析。拔出强度或骨与植入物接触方面没有差异。然而，microCT和组织形态计量学分析均显示，与实心植入物相比，多孔植入物的新骨体积显著更高。观察到骨长入多孔植入物的孔隙中，尤其是在植入物与皮质骨交界的根尖部分附近。这些结果表明，具有微观/纳米尺度表面粗糙度和受松质骨启发的孔隙率的激光烧结Ti-6Al-4V植入物可促进骨生长，并且可作为骨界面植入物实心植入物的优质替代品。
