Table1_Unleashing innovation: 3D-printed biomaterials in bone tissue engineering for repairing femur and tibial defects in animal models – a systematic review and meta-analysis.docx

Introduction3D-printed scaffolds have emerged as an alternative for addressing the current limitations encountered in bone reconstruction. This study aimed to systematically review the feasibility of using 3D bio-printed scaffolds as a material for bone grafting in animal models, focusing on femoral and tibial defects. The primary objective of this study was to evaluate the efficacy, safety, and overall impact of these scaffolds on bone regeneration.
MethodsElectronic databases were searched using specific search terms from January 2013 to October 2023, and 37 relevant studies were finally included and reviewed. We documented the type of scaffold generated using the 3D printed techniques, detailing its characterization and rheological properties including porosity, compressive strength, shrinkage, elastic modulus, and other relevant factors. Before incorporating them into the meta-analysis, an additional inclusion criterion was applied where the regenerated bone area (BA), bone volume (BV), bone volume per total volume (BV/TV), trabecular thickness (Tb. Th.), trabecular number (Tb. N.), and trabecular separation (Tb. S.) were collected and analyzed statistically.
Results3D bio-printed ceramic-based composite scaffolds exhibited the highest capacity for bone tissue regeneration (BTR) regarding BV/TV of femoral and tibial defects of animal models. The ideal structure of the printed scaffolds displayed optimal results with a total porosity >50% with a pore size ranging between 300- and 400 µM. Moreover, integrating additional features and engineered macro-channels within these scaffolds notably enhanced BTR capacity, especially observed at extended time points.
DiscussionIn conclusion, 3D-printed composite scaffolds have shown promise as an alternative for addressing bone defects.

引言
3D打印支架（3D-printed scaffolds）已成为解决骨重建领域当前存在局限的替代方案。本研究旨在系统评估3D生物打印支架（3D bio-printed scaffolds）用作动物模型骨移植材料的可行性，重点聚焦股骨与胫骨骨缺损模型。本研究的核心旨在评估此类支架在骨再生方面的效能、安全性及整体影响。

研究方法
本研究于2013年1月至2023年10月期间，通过特定检索词检索电子数据库，最终纳入并综述37项相关研究。我们记录了3D打印技术制备的支架类型，并详细阐述其表征参数与流变学特性，包括孔隙率、抗压强度、收缩率、弹性模量及其他相关影响因素。在纳入荟萃分析前，我们增设一项纳入标准：对再生骨面积（bone area, BA）、骨体积（bone volume, BV）、骨体积与总体积之比（bone volume per total volume, BV/TV）、骨小梁厚度（trabecular thickness, Tb. Th.）、骨小梁数量（trabecular number, Tb. N.）以及骨小梁分离度（trabecular separation, Tb. S.）进行收集与统计学分析。

研究结果
在动物模型股骨与胫骨骨缺损的骨体积与总体积之比（BV/TV）指标上，3D生物打印陶瓷基复合支架展现出最优的骨组织再生（bone tissue regeneration, BTR）能力。打印支架的理想结构呈现最优效果：总孔隙率大于50%，孔径范围为300~400微米。此外，在支架中集成额外功能结构与定制化大通道，可显著提升骨组织再生能力，该效果在较长时间观测节点中尤为明显。

讨论
综上，3D打印复合支架已展现出作为骨缺损修复替代方案的应用潜力。