Azarnoosh M, Stoffel M, Quack V, Betsch M, Rath B, Tingart M, Markert B
RWTH Aachen University, Institute of General Mechanics, Templergraben 64, 52062 Aachen, Germany.
RWTH Aachen University, Institute of General Mechanics, Templergraben 64, 52062 Aachen, Germany.
J Mech Behav Biomed Mater. 2017 May;69:169-177. doi: 10.1016/j.jmbbm.2016.12.010. Epub 2016 Dec 21.
Limited availability of fresh intervertebral discs (IVDs) necessitates the use of frozen-thawed samples in biomechanical investigations. Several authors have reported the mechanical properties of frozen-thawed IVDs, but few studies have investigated the effects of storage temperature and cooling rate. The validity and reliability of the applied freezing-thawing procedures are still relatively unknown. The study aims to compare the mechanical responses of fresh porcine IVDs and porcine IVDs, which were frozen at different freezing temperatures with a controlled-rate cooling process and then thawed. The specimens were obtained from pigs aged 6 months. A total of 18 functional spine units (FSUs) were taken from seven porcine lumbar spines (L1-L6). The specimens were then split into three groups. The first group was tested fresh immediately and the other two groups were frozen at the same cooling rate and stored at -20°C and -80°C, respectively, before testing. The period of storage ranged between 12 and 43 days. The frozen specimens were thawed for 9h at room temperature before the tests. A special IVD bioreactor, which maintained the realistic behaviour of IVDs under various loading conditions, was developed. The analysis of variance (ANOVA) was used to determine if the observed results were statistically significant. The results indicated that frozen storage at -20°C decreases the comprehensive stiffness. In contrast, freezing to -80°C did not seem to have any effect on the mechanical properties of IVDs. No significant differences in outcome were observed for the samples, which had different spine levels. The study confirmed the reliability and usability of frozen-thawed samples stored at -80°C for biomechanical investigations.
新鲜椎间盘（IVD）的可获取性有限，这使得在生物力学研究中需要使用冻融样本。几位作者报告了冻融IVD的力学性能，但很少有研究调查储存温度和冷却速率的影响。所应用的冻融程序的有效性和可靠性仍然相对未知。本研究旨在比较新鲜猪IVD和在不同冷冻温度下通过控速冷却过程冷冻然后解冻的猪IVD的力学响应。样本取自6个月大的猪。从七头猪的腰椎（L1 - L6）中总共获取了18个功能脊柱单元（FSU）。然后将样本分成三组。第一组立即进行新鲜测试，另外两组以相同的冷却速率冷冻，分别储存在-20°C和-80°C，然后进行测试。储存期在12至43天之间。冷冻样本在测试前在室温下解冻9小时。开发了一种特殊的IVD生物反应器，该反应器能在各种加载条件下保持IVD逼真的行为。使用方差分析（ANOVA）来确定观察结果是否具有统计学意义。结果表明，在-20°C下冷冻储存会降低综合刚度。相比之下，冷冻至-80°C似乎对IVD的力学性能没有任何影响。对于不同脊柱节段的样本，未观察到结果有显著差异。该研究证实了储存在-80°C的冻融样本用于生物力学研究的可靠性和可用性。
