Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
J Orthop Res. 2023 Apr;41(4):823-833. doi: 10.1002/jor.25424. Epub 2022 Aug 22.
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 ) 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.
经 25-35kGy 标准γ射线辐射消毒的皮质骨移植物与未辐照骨相比，其静态和循环抗断裂能力降低。为了减轻辐射损伤，我们最近观察到 0 至 25kGy 辐照的人皮质骨的高周疲劳行为呈剂量依赖性，较低剂量的疲劳寿命呈对数延长。本研究的目的如下：（1）确定人皮质骨的断裂韧性、断裂功和疲劳裂纹扩展阻力是否也与辐射剂量有关，（2）确定辐射剂量和用于评估胶原无序性的拉曼生物标志物与断裂性能的相关性。从两个供体股骨对中加工出紧凑拉伸试件，并分配到四个处理组：0（未辐照对照）、10、17.5 和 25kGy。断裂韧性试件在单调加载至破坏的条件下进行加载，确定临界应力强度因子（K）。从加载至破坏的位移积分计算断裂功。疲劳裂纹扩展试件在恒定室温灌溉下循环加载，计算疲劳裂纹扩展速率（da/dN）和循环应力强度（∆K）。从 0 至 25kGy，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）。辐射剂量比胶原无序性更能预测断裂性能。这些发现支持在该剂量范围内皮质骨的准静态和疲劳断裂性能与辐射剂量有关。导致这些断裂阻力损失的辐射引起的结构改变仍有待阐明。
