Cortical bone allograft sterilized with a standard γ-radiation dose of 25–35kGy has demonstrated reduced static and cyclic fracture resistance compared with unirradiated bone. To mitigate radiation damage, we recently observed a dose-dependent response of high-cycle fatigue behavior of human cortical bone from 0 to 25 kGy, with lower doses exhibiting logarithmically longer fatigue lives. The objectives of this study were as follows: (1) to determine whether fracture toughness, work-to-fracture, and fatigue crack propagation resistance of human cortical bone are also radiation dose-dependent, and (2) to determine the associations of radiation dose and a Raman biomarker for collagen disorder with fracture properties. Compact tension specimens were machined from two donor femoral pairs and allocated to four treatment groups: 0 (unirradiated control), 10, 17.5, and 25 kGy. Fracture toughness specimens were monotonically loaded to failure and the critical stress intensity factor (K_C) was determined. Work-to-fracture was calculated from the load versus displacement integral up to fracture. Fatigue crack propagation specimens were cyclically loaded under constant room-temperature irrigation and fatigue crack growth rate (da/dN) and cyclic stress intensity (∆K) were calculated. Fracture toughness, work-to-fracture, and fatigue crack propagation resistance decreased 18%, 33%, and 15-fold from 0 to 25 kGy, respectively (p < 0.05). Radiation dose was more predictive of fracture properties than collagen disorder. These findings support that quasi-static and fatigue fracture properties of cortical bone are radiation dose-dependent within this dose range. The structural alterations arising from irradiation that cause these losses in fracture resistance remain to be elucidated.

中文翻译：

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皮质骨的疲劳裂纹扩展和断裂韧性与辐射剂量相关


与未照射的骨相比，用 25-35kGy 标准 γ 辐射剂量灭菌的皮质骨同种异体移植物已证明其静态和循环断裂阻力降低。为了减轻辐射损伤，我们最近观察到人体皮质骨在 0 至 25 kGy 的高周疲劳行为中出现剂量依赖性反应，较低剂量表现出对数更长的疲劳寿命。本研究的目的如下：(1) 确定人体皮质骨的断裂韧性、断裂功和疲劳裂纹扩展阻力是否也与辐射剂量相关，(2) 确定辐射的关联剂量和具有断裂特性的胶原蛋白紊乱的拉曼生物标志物。紧凑张力样本由两对供体股骨加工而成，并分配到四个处理组：0（未照射对照）、10、17.5 和 25 kGy。将断裂韧性样品单调加载至失效并确定临界应力强度因子 ( K _C )。断裂功是根据断裂前的载荷与位移积分来计算的。疲劳裂纹扩展试样在恒定室温冲洗下进行循环加载，并计算疲劳裂纹扩展速率（ da / dN ）和循环应力强度（ ΔK ）。从 0 到 25 kGy，断裂韧性、断裂功和疲劳裂纹扩展阻力分别降低了 18%、33% 和 15 倍 ( p < 0.05)。放射剂量比胶原蛋白紊乱更能预测骨折特性。这些发现支持皮质骨的准静态和疲劳断裂特性在此剂量范围内依赖于辐射剂量。 辐照引起的结构改变导致抗断裂性损失仍有待阐明。