The mechanical behaviour of regenerated bone tissue during fracture healing is key in determining its ability to withstand physiological loads. However, the strain distribution in the newly formed tissue and how this influences the way a fracture heals it is still unclear. X-ray Computed Tomography (XCT) has been extensively used to assess the progress of mineralised tissues in regeneration and when combined with in situ mechanics and digital volume correlation (DVC) has been proven a powerful tool to understand the mechanical behaviour and full-field three-dimensional (3D) strain distribution in bone. The purpose of this study is therefore to use in situ XCT mechanics and DVC to investigate the strain distribution and load-bearing capacity in a regenerating fracture in the diaphyseal bone, using a rodent femoral fracture model stabilised by external fixation. Rat femurs with 1 mm and 2 mm osteotomy gaps were tested under in situ XCT step-wise compression in the apparent elastic region. High strain was present in the newly formed bone (ε_p1 and ε_p3 reaching 29 000 µε and –43 000 µε, respectively), with a wide variation and inhomogeneity of the 3D strain distribution in the regenerating tissues of the fracture gap, which is directly related to the presence of unmineralised tissue observed in histological images. The outcomes of this study will contribute in understanding natural regenerative ability of bone and its mechanical behaviour under loading.

中文翻译：

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股骨骨折模型中再生骨组织的全场应变

骨折愈合过程中再生骨组织的力学行为是决定其承受生理负荷能力的关键。然而，新形成的组织中的应变分布以及这如何影响骨折愈合的方式仍不清楚。X 射线计算机断层扫描 (XCT) 已广泛用于评估矿化组织在再生过程中的进展，当与原位力学和数字体积相关 (DVC) 相结合时，已被证明是了解力学行为和全场的有力工具骨骼中的三维 (3D) 应变分布。因此，本研究的目的是使用原位 XCT 力学和 DVC 来研究骨干骨再生骨折中的应变分布和承载能力，使用通过外固定装置稳定的啮齿动物股骨骨折模型。在表观弹性区域的原位 XCT 逐步压缩下测试具有 1 mm 和 2 mm 截骨间隙的大鼠股骨。新形成的骨骼中存在高应变（ε_p1和 ε _p3分别达到 29 000 µε 和 –43 000 µε），骨折间隙再生组织中的 3D 应变分布变化很大且不均匀，这与组织学中观察到的未矿化组织的存在直接相关图片。这项研究的结果将有助于了解骨骼的自然再生能力及其在负载下的机械行为。