Bursa Technical University, Department of Mechanical Engineering, Bursa, Türkiye.
Bursa Technical University, Department of Mechanical Engineering, Bursa, Türkiye; Bursa Technical University, Department of Polymer Materials Engineering, Bursa, Türkiye.
Comput Biol Med. 2024 Dec;183:109227. doi: 10.1016/j.compbiomed.2024.109227. Epub 2024 Oct 5.
Large or carcinogenic bone defects may require a challenging bone tissue scaffold design ensuring a proper mechanobiological setting. Porosity and biodegradation rate are the key parameters controlling the bone-remodeling process. PLA presents a great potential for geometrically flexible 3-D scaffold design. This study aims to investigate the mechanical variation throughout the biodegradation process for lattice-type PLA scaffolds using both experimental observations and simulations. Three different unit-cell geometries are used for creating the scaffolds: basic cube (BC), body-centered structure (BCS), and body-centered cube (BCC). Three different porosity ratios, 50 %, 62.5 %, and 75 %, are assigned to all three structures by altering their strut dimensions. 3-D printed scaffolds are soaked in PBS solution at 37 °C for 15, 30, 60, 90, and 120 days both unloaded and under dead load. Water absorption, weight loss, and compression stiffness are measured to characterize the first-stage degradation and investigate the possible influences of these parameters on the whole biodegradation process. The strength reduction stage of biodegradation is simulated by solving pseudo-first-order kinetics-based molecular weight change equation using FEA with equisized cubic (voxel-like) elements. For the first stage, mechanical load does not have a statistically significant effect on biodegradation. BCC with 62.5 % porosity shows a maximum water absorption rate of around 25 % by the 60th day which brings an advantage in creating an aquatic environment for cell growth. Results indicate a significant water deposition inside almost all scaffolds and water content is determined to be the main reason for the retained or increased compression stiffness. A distinguishable stiffness increase in the initial degradation process occurs for 75 % porous BC and 50 % porous BCC scaffolds. Following the quasi-stable stage of biodegradation, almost all scaffolds lost their rigidity by around 44-48 % within 120 days based on numerical results. Therefore, initial stiffness increase in the quasi-stable stage of biodegradation can be advantageous and BCC geometry with a porosity between 50% and 62 % is the optimum solution for the whole biodegradation process.
大或致癌性的骨缺损可能需要具有挑战性的骨组织支架设计，以确保适当的机械生物学环境。孔隙率和降解速率是控制骨重塑过程的关键参数。PLA 为几何形状灵活的 3D 支架设计提供了巨大的潜力。本研究旨在通过实验观察和模拟研究晶格型 PLA 支架在整个降解过程中的力学变化。使用三种不同的单元结构来创建支架：基本立方体（BC）、体心结构（BCS）和体心立方体（BCC）。通过改变它们的支柱尺寸，为所有三种结构分配了三个不同的孔隙率比，即 50%、62.5%和 75%。3D 打印的支架在 37°C 的 PBS 溶液中浸泡 15、30、60、90 和 120 天，分别在无负载和负重下进行。通过测量吸水率、失重和压缩刚度来表征第一阶段的降解，并研究这些参数对整个降解过程的可能影响。通过使用具有等尺寸立方（体素样）单元的有限元分析（FEA）来解决基于拟一级动力学的分子量变化方程，模拟生物降解的强度降低阶段。对于第一阶段，机械负载对生物降解没有统计学上的显著影响。62.5%孔隙率的 BCC 在第 60 天达到约 25%的最大吸水率，这为细胞生长创造水生环境带来了优势。结果表明，几乎所有支架内部都有明显的水分沉积，水分含量被确定为保持或增加压缩刚度的主要原因。在初始降解过程中，75%多孔 BC 和 50%多孔 BCC 支架出现明显的刚度增加。在生物降解的准稳定阶段之后，根据数值结果，几乎所有支架在 120 天内失去了约 44-48%的刚性。因此，在准稳定阶段的初始刚度增加可能是有利的，孔隙率在 50%和 62%之间的 BCC 几何形状是整个生物降解过程的最佳解决方案。
