Department of Mechanical Engineering, National Institute of Technology, Uttarakhand, India.
Department of Mechanical Engineering, National Institute of Technology, Uttarakhand, India.
J Mech Behav Biomed Mater. 2023 Oct;146:106061. doi: 10.1016/j.jmbbm.2023.106061. Epub 2023 Aug 3.
A methodology has been developed in this work to design customized cranial implants from computed tomography (CT) scan images for symmetric as well as asymmetric defects. The two-dimensional CT scan images were converted into three-dimensional geometric models using software packages. Two cases of cranial cavities at different locations were considered for implant design using two different approaches. Case 1 is having a symmetric cranial cavity while Case 2 has an asymmetric frontal cranial cavity. The craniums with defects were 3D reconstructed. Customized cranial implants were made for the two cases. In Case 1, symmetry was used to design the cranial implant. Symmetry cannot be used in Case 2. In Case 2, the implant was designed by blending from the surface available adjacent to the missing portion of the cranium. 3D reconstructed bone models and customized implants were 3D printed in poly-lactic acid (PLA) using a fused deposition modeling process for form and fit evaluation. Finite element analysis was performed to compare the mechanical behavior of bone, and the two biomaterials - polyether ether ketone (PEEK), and Ti6Al4V. Static structural finite element analysis was performed to simulate the impact of falling off a bicycle with an impact on the cranial implants in the two cases. The load was modeled as a normal force acting on the surface of the implant. It was found that the stresses in the titanium alloy are comparable to those of PEEK for both the cases. However, the strains and deformation were found to be much smaller compared to those in PEEK. Therefore, the titanium alloy is the material of choice for both the cases among the materials under consideration. The designed implants are solid hence may face the challenge in bone ingrowth. In future studies, the implant can be made porous by incorporating a lattice structure to enhance osseointegration and promote bone ingrowth. Implants for both symmetric and asymmetric defect cases in cranium were successfully designed.
这项工作中开发了一种方法，用于从计算机断层扫描（CT）扫描图像设计定制化颅骨植入物，适用于对称和不对称缺陷。使用软件包将二维 CT 扫描图像转换为三维几何模型。使用两种不同的方法考虑了两个不同位置的颅骨腔进行植入物设计。病例 1 具有对称的颅骨腔，而病例 2 具有不对称的额骨颅骨腔。有缺陷的颅骨进行了 3D 重建。为这两个病例制作了定制化颅骨植入物。在病例 1 中，使用对称性设计颅骨植入物。病例 2 不能使用对称性。在病例 2 中，通过与颅骨缺失部分相邻的表面混合来设计植入物。使用熔融沉积建模工艺，使用聚乳酸（PLA）对 3D 重建的骨模型和定制植入物进行 3D 打印，以进行形状和适配性评估。进行有限元分析以比较两种生物材料-聚醚醚酮（PEEK）和 Ti6Al4V-的骨和机械性能。进行静态结构有限元分析，以模拟在两个病例中颅骨植入物受到自行车摔倒冲击的情况。将力建模为作用在植入物表面的法向力。结果发现，在两种情况下，钛合金的应力与 PEEK 的应力相当。然而，与 PEEK 相比，应变和变形要小得多。因此，钛合金是在所考虑的材料中，两种情况下颅骨植入物的首选材料。设计的植入物是实心的，因此可能面临骨向内生长的挑战。在未来的研究中，可以通过加入晶格结构使植入物多孔化，以增强骨整合并促进骨向内生长。成功设计了用于对称和不对称颅骨缺陷病例的植入物。
