Hongo Michio, Gay Ralph E, Hsu Jui-Ting, Zhao Kristin D, Ilharreborde Brice, Berglund Lawrence J, An Kai-Nan
Division of Orthopedic Research, Mayo Clinic College of Medicine, Rochester, MN, USA.
J Biomech. 2008;41(4):916-20. doi: 10.1016/j.jbiomech.2007.11.003. Epub 2008 Feb 20.
Fresh frozen spine specimens are commonly used in biomechanical investigations of the spine. Since many study designs require staged preparation and testing, the effect of multiple freeze-thaw cycles on motion behavior should be understood. The objective of this study was to investigate the effect of multiple freeze-thaw cycles on the biomechanical parameters measured during dynamic pure moment loading. Ten porcine lumbar motion segments were harvested immediately after death and potted in acrylic fixtures. Specimens were tested in continuous pure moment flexion-extension, lateral flexion, and rotation cycles up to a limit of +/-5Nm. Moment-angular displacement data were analyzed and parameters quantified including range of motion, elastic zone, transitional zone (neutral region) size and slope, and width of the hysteresis loop. All specimens were tested at baseline and after each of three subsequent cycles of freezing and thawing. The transitional zone size decreased and the transitional zone slope increased during flexion-extension and lateral bending after the initial freeze-thaw cycle. These parameters were not altered after subsequent cycles. No significant change was observed in the elastic zone or width of hysteresis loop. Although freezing porcine spine specimens increased the stiffness in the neutral region of motion, up to three subsequent cycles of freezing and thawing did not further affect these motion characteristics. This suggests that data obtained from porcine spines which have been frozen and thawed multiple times are stable after initial freezing.
新鲜冷冻的脊柱标本常用于脊柱的生物力学研究。由于许多研究设计需要分阶段制备和测试，因此应了解多次冻融循环对运动行为的影响。本研究的目的是调查多次冻融循环对动态纯力矩加载过程中测量的生物力学参数的影响。十段猪腰椎运动节段在死后立即采集，并植入丙烯酸固定装置中。对标本进行连续的纯力矩屈伸、侧屈和旋转循环测试，直至极限为+/-5Nm。分析力矩-角位移数据并量化参数，包括运动范围、弹性区、过渡区（中性区域）大小和斜率以及滞后环宽度。所有标本在基线时以及随后三个冻融循环中的每一个循环后进行测试。在第一次冻融循环后，屈伸和侧弯过程中过渡区大小减小，过渡区斜率增加。在随后的循环中这些参数没有改变。弹性区或滞后环宽度没有观察到显著变化。虽然冷冻猪脊柱标本增加了运动中性区域的刚度，但随后多达三个冻融循环并未进一步影响这些运动特征。这表明，多次冻融的猪脊柱获得的数据在初次冷冻后是稳定的。
