Department of Materials Science and Engineering, Institute of Glass and Ceramics, Friedrich-Alexander Universität Erlangen-Nürnberg, Martensstr. 5, D-91058 Erlangen, Germany.
Department of Materials Science and Engineering, Institute of Glass and Ceramics, Friedrich-Alexander Universität Erlangen-Nürnberg, Martensstr. 5, D-91058 Erlangen, Germany; Frontier Research Institute for Materials Science, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Acta Biomater. 2018 Oct 15;80:390-400. doi: 10.1016/j.actbio.2018.09.008. Epub 2018 Sep 11.
Ideal artificial bone grafts aim for multiscale porosity, high mechanical strength and ensure rapid vascularization for bone ingrowth. In this work modular ceramic arteriovenous loops (AV-loops) with a hierarchical porosity approach were designed and manufactured to meet these criteria and to exceed the poor mechanical strength of monolithic scaffolds. Bioactive building blocks (β-TCP, HAp, BCP) with dimensions of 1.5-3.0 mm were prepared by injection molding and assembled to complex AV-loop scaffolds using a customized automated assembly technology (pick and place). The building blocks were bonded with a biocompatible adhesive. Single building blocks are characterized by a compressive strength of 112.4-134.5 MPa with a residual sintering porosity of 32.2-41.5%, matching the strength of cortical bone of 100-230 MPa. The compressive strength of the modular assemblies varied between 22.3 and 47.6 MPa primary depending on the building block arrangement. The achieved compressive strengths are superior to current monolithic AV-scaffolds and sufficient for the implantation as non-load-bearing AV-loop scaffolds in isolation chambers. The modular AV-loop scaffolds provide a hierarchical interconnected pore network (P = 58.8%) combining small macropores of 4.1-4.3 µm size for possible enhanced protein absorption and large gradient macropores of 200-1700 µm size for optimum vascularization and complete bone ingrowth. The modular building block approach allows to design patient individualized scaffolds with complex hierarchical pore networks. The pore volume, size and geometry as well as the biological response can effectively be tuned by changing the dimensions, shape and placing gap of the bioactive building blocks. STATEMENT OF SIGNIFICANCE: Gold standard of bone replacement in case of surgery or cancer is still own bone material usually taken from the hip/arm or leg in second surgery with poor mechanical properties and limited amount. To avoid a second surgery and provide mechanical strong scaffold structures for fast patient regeneration a novel modular building block approach is used. This allows complex scaffold geometry with a hierarchical interconnection porosity for blood vessel ingrowth. The pore volume, size and geometry as well as the biological response can effectively be tuned by changing the dimensions, shape and placing gap of the bioactive building blocks.
理想的人工骨移植物需要具有多尺度孔隙率、高强度机械性能，并确保快速血管化以促进骨长入。在这项工作中，设计并制造了具有层次化孔隙率的模块化陶瓷动静脉环（AV 环），以满足这些标准，并克服整体支架机械强度差的问题。采用注射成型技术制备尺寸为 1.5-3.0mm 的生物活性构建块（β-TCP、HAp、BCP），并使用定制的自动化装配技术（拾取和放置）将其组装到复杂的 AV 环支架中。构建块通过生物相容性粘合剂进行粘合。单个构建块的抗压强度为 112.4-134.5MPa，残余烧结孔隙率为 32.2-41.5%，与 100-230MPa 的皮质骨强度相匹配。模块化组件的抗压强度主要取决于构建块的排列方式，在 22.3-47.6MPa 之间变化。所达到的抗压强度优于目前的整体 AV 支架，足以作为非承重 AV 环支架单独植入隔离室。模块化 AV 环支架提供了一种层次化的互联孔网络（P=58.8%），结合了 4.1-4.3µm 大小的小尺寸宏观孔，以实现可能增强的蛋白质吸收，以及 200-1700µm 大小的大梯度宏观孔，以实现最佳的血管化和完全的骨长入。模块化构建块方法允许设计具有复杂层次化孔网络的患者个体化支架。通过改变生物活性构建块的尺寸、形状和放置间隙，可以有效地调整孔隙率、大小和几何形状以及生物学反应。
在手术或癌症的情况下，骨置换的金标准仍然是自身骨材料，通常在第二次手术中从臀部/手臂或腿部取出，具有较差的机械性能和有限的数量。为了避免第二次手术并为患者快速再生提供机械强度高的支架结构，采用了一种新的模块化构建块方法。这允许使用具有层次化互连通孔的复杂支架几何形状，以促进血管长入。通过改变生物活性构建块的尺寸、形状和放置间隙，可以有效地调整孔隙率、大小和几何形状以及生物学反应。
