Zhang Guanjun, Deng Xianpan, Guan Fengjiao, Bai Zhonghao, Cao Libo, Mao Haojie
State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China.
Science and Technology on Integrated Logistics Support Laboratory, National University of Defense Technology, Changsha 410073, China.
Clin Biomech (Bristol). 2018 Aug;57:56-66. doi: 10.1016/j.clinbiomech.2018.06.003. Epub 2018 Jun 6.
The use of saline in preserving bone specimens may affect the mechanical properties of specimens. Yet, the reported effects varied and contradicted to each other, with a lack of investigating constitutive material parameters. Therefore, we quantified the effects of preservation time on the constitutive properties of cortical bone.
We collected 120 specimens from the mid-diaphysis of six male bovine femora, which were assigned to five groups, including fresh-frozen for 60 days (-20 °C), storage in saline for 3, 10, 36 and 60 days (25 °C). All specimens underwent quasi-static three-point bending tests with a loading rate of 0.02 mm/s. Using the optimization method combined with specimen-specific finite element models, the Young's modulus, tangent modulus, yield stress, effective plastic strain, yield strain, ultimate stress, and toughness were calculated.
Saline preservation resulted in a significant decrease of Young's modulus, yield stress, ultimate stress and pre-yield toughness (P < 0.001), and a significant increase of effective plastic strain (P = 0.034). After 10 days of preservation, yield stress and pre-yield toughness decreased -14.9% and -21.4%, respectively, and they continued to decrease with longer preservation time. After 36 days of preservation, Young's modulus and ultimate stress decreased -19.2% and -17.3%, respectively, and continued to decrease with longer preservation time. Our data also showed changes of material properties collected after 3-day saline preservation, while the low statistical power must be considered for this group.
Saline preservation impacts on mechanical properties of cortical bone tissue and the effect is already observable after 3 days.
使用生理盐水保存骨标本可能会影响标本的力学性能。然而，报告的影响各不相同且相互矛盾，且缺乏对本构材料参数的研究。因此，我们量化了保存时间对皮质骨本构特性的影响。
我们从六只雄性牛股骨的中骨干收集了120个标本，将其分为五组，包括在-20°C下新鲜冷冻60天、在25°C的生理盐水中保存3天、10天、36天和60天。所有标本均以0.02mm/s的加载速率进行准静态三点弯曲试验。使用优化方法结合特定标本的有限元模型，计算杨氏模量、切线模量、屈服应力、有效塑性应变、屈服应变、极限应力和韧性。
生理盐水保存导致杨氏模量、屈服应力、极限应力和屈服前韧性显著降低（P<0.001），有效塑性应变显著增加（P=0.034）。保存10天后，屈服应力和屈服前韧性分别下降了14.9%和21.4%，并且随着保存时间的延长继续下降。保存36天后，杨氏模量和极限应力分别下降了19.2%和17.3%，并随着保存时间的延长继续下降。我们的数据还显示了3天生理盐水保存后收集的材料性能变化，不过该组的统计功效较低，必须予以考虑。
生理盐水保存会影响皮质骨组织的力学性能，且在3天后即可观察到这种影响。
