Singh R, Lee P D, Lindley Trevor C, Dashwood R J, Ferrie Emilie, Imwinkelried T
Department of Materials, Imperial College London, Exhibition Road, SW7 2AZ, UK.
Acta Biomater. 2009 Jan;5(1):477-87. doi: 10.1016/j.actbio.2008.06.014. Epub 2008 Jul 1.
Titanium foams produced via the space-holder method are used for spinal fusion devices since their combination of an open-cell structure and bone-like mechanical properties promises potentially excellent bone ingrowth. Earlier studies have indicated that the size of the pores and interconnects must be greater than 100microm for effective bone ingrowth and vascularization. Hence, the quantification of the pore and interconnect size is required for efficient scaffold design. In this study, microcomputed tomography (microCT) was used to obtain the three-dimensional (3D) structure of Ti foams with three levels of porosity (51%, 65% and 78%). Novel algorithms were then applied to quantify both the pore and interconnect size of Ti foams as a function of porosity. All foams possessed a modal pore and interconnect size in excess of 300microm, satisfying the requirement of being greater than 100microm. The pore and interconnect size also dominates the flow properties or permeability of open-cell structures. Therefore, the microCT data was also used to generate a mesh for computational fluid dynamics analysis to predict the permeability. The calculated permeability (117-163x10(-12)m(2) depending on direction) for the Ti foams with 65% porosity was first validated against experimental measurements (98-163x10(-12)m(2)) and then compared to prior authors' measurements in healthy cancellous bovine bone (233-465x10(-12)m(2)). The close match among all the permeability values proves the suitability of the material for biomedical skeletal-implant applications.
通过空间保持法制备的泡沫钛被用于脊柱融合装置，因为其开孔结构和类骨力学性能的结合有望实现优异的骨长入。早期研究表明，为实现有效的骨长入和血管化，孔隙和连通孔的尺寸必须大于100微米。因此，为了进行高效的支架设计，需要对孔隙和连通孔尺寸进行量化。在本研究中，使用微型计算机断层扫描（microCT）来获取具有三种孔隙率水平（51%、65%和78%）的泡沫钛的三维（3D）结构。然后应用新算法来量化泡沫钛的孔隙和连通孔尺寸与孔隙率的函数关系。所有泡沫的模态孔隙和连通孔尺寸均超过300微米，满足大于100微米的要求。孔隙和连通孔尺寸还主导着开孔结构的流动特性或渗透率。因此，microCT数据还被用于生成网格以进行计算流体动力学分析，从而预测渗透率。首先将孔隙率为65%的泡沫钛的计算渗透率（根据方向不同，为117 - 163×10⁻¹²平方米）与实验测量值（98 - 163×10⁻¹²平方米）进行验证，然后与先前作者在健康松质牛骨中的测量值（233 - 465×10⁻¹²平方米）进行比较。所有渗透率值之间的紧密匹配证明了该材料适用于生物医学骨骼植入应用。
