ABSTRACT

Current intervertebral fusion devices present multiple complication risks such as a lack of fixation, device migration and subsidence. An emerging solution to these problems is the use of additively manufactured lattice structures that are mechanically compliant and permeable to fluids, thus promoting osseointegration and reducing complication risks. Strut-based diamond and sheet-based gyroid lattice configurations having a pore diameter of 750 µm and levels of porosity of 60, 70 and 80% are designed and manufactured from Ti-6Al-4V alloy using laser powder bed fusion. The resulting structures are CT–scanned, compression tested and subjected to fluid permeability evaluation. The stiffness of both structures (1.9–4.8 GPa) is comparable to that of bone, while their mechanical resistance (52–160 MPa) is greater than that of vertebrae (3–6 MPa), thus decreasing the risks of wither bone or implant failure. The fluid permeability (5–57 × 10⁻⁹ m²) and surface-to-volume ratios (~3) of both lattice structures are close to those of vertebrae. This study shows that both types of lattice structures can be produced to suit the application specifications within certain limits imposed by physical and equipment-related constraints, providing potential solutions for reducing the complication rate of spinal devices by offering a better fixation through osseointegration.

摘要

当前的椎间融合器具有多种并发症风险，例如缺乏固定，器械迁移和下陷。解决这些问题的一种新兴解决方案是使用可机械顺应且可渗透流体的增材制造的晶格结构，从而促进骨整合并降低并发症风险。由Ti-6Al-4V合金通过激光粉末床熔合设计和制造具有750 µm的孔隙度和60％，70％和80％的孔隙率的基于支撑的金刚石和基于薄片的回旋晶格结构。所得结构经过CT扫描，压缩测试并进行了流体渗透性评估。两种结构的刚度（1.9–4.8 GPa）与骨骼相当，而其机械阻力（52–160 MPa）大于椎骨（3–6 MPa），从而降低了骨萎缩或植入物衰竭的风险。流体渗透率（5–57×10两种晶格结构的（^-9  m ²）和表面积/体积比（〜3）都接近椎骨。这项研究表明，两种类型的晶格结构都可以在与物理和设备相关的约束所施加的特定限制内生产出来，以适应应用规范，从而通过骨整合提供更好的固定，从而为降低脊柱器械的并发症发生率提供了潜在的解决方案。