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Abstract: The specific surface area (SS) and pore size (D) exhibit an inherent trade-off in the microscale design of bone implants: larger pores typically correlate with reduced surface area and vice versa. This relationship has attracted notable attention because of its critical role in the regulation of cell adhesion and osteogenesis. However, it remains largely unclear howSSandDaffect the generated bone tissue and dynamically change during long-term osteogenesis. Herein, by applying rigorous geometric mapping to minimal surfaces, we constructed precisely partitioned and layer-by-layer thickened tissue models to simulate osteogenesis across different temporal scales and thereby track the dynamic evolution of geometric characteristics, permeability, and mechanobiological tissue differentiation. The high-SSsamples were found to facilitate the rapid formation of new bone tissue in the early stages. However, their smaller pores tended to cause occlusions, hindering further tissue development. In contrast, low-SSsamples showed slower bone regeneration, but their larger pores provided adequate physical space for tissue regeneration and mass transport, ultimately promoting bone formation in the long term. Mechanobiological regulation suggests that fibrous tissue formation inhibits additional bone formation, establishing a dynamic equilibrium between osteogenesis and pore space to sustain nutrient/waste exchange throughout the regenerative process. Overall, smaller pores are preferable in implants for minimally loaded osteoplasty procedures focused on early-stage bone consolidation, whereas larger pores are preferable in dynamically loaded implants requiring prolonged mechanical stability.

Effect of surface area and pore size on long-term bone regeneration: dynamic changes in geometric characteristics, mass transport, and mechanobiology

在骨植入体的微尺度设计中, 比表面积 (SS) 与孔径 (D) 存在固有的制约关系: 孔径增大会导致表面积缩减, 这种关联因对细胞黏附和成骨过程调控的关键作用而备受关注。 然而, 比表面积与孔径如何影响新生骨组织并在长期成骨过程中动态变化尚不明确。 本研究通过极小曲面的严格几何映射, 构建了精确分区且逐层增厚的组织模型, 以模拟不同时间尺度的成骨过程, 进而追踪几何特征、 渗透性及组织分化的动态演变。 研究发现, 高比表面积样本在早期能促进新骨组织快速形成, 但其较小的孔径易导致孔隙闭塞, 阻碍组织进一步发育; 而低比表面积样本虽成骨速率较缓, 较大孔径却为组织再生与物质传输提供了充足的物理空间, 最终实现更优的远期成骨效果。 力生物学计算模型表明, 骨组织增厚会驱动纤维组织形成从而抑制更多的骨组织生成, 由此在成骨与孔隙结构间建立动态平衡, 确保骨再生各阶段的营养与废物交换。 总体而言, 侧重早期骨整合的低负荷骨植入体宜优先采用小孔径/高比表面积设计; 而需长期骨再生的高负荷植入体则更适合大孔隙结构方案。
Minimal surface; Specific surface area; Pore size; Bone ingrowth; Mechanobiology; Finite element simulation