Nazarian Ara, Hermannsson Bryan J, Muller John, Zurakowski David, Snyder Brian D
Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA.
J Biomech. 2009 Jan 5;42(1):82-6. doi: 10.1016/j.jbiomech.2008.09.037. Epub 2008 Dec 9.
Murine bone specimens are used extensively in skeletal research to assess the effects of environmental, physiologic and pathologic factors on their mechanical properties. Given the destructive nature of mechanical testing, it is normally performed as a terminal procedure, where specimens must be preserved without affecting their mechanical properties. To this end, we aimed to study the effects of tissue preservation (freezing and formalin fixation) on the elastic and viscoelastic mechanical properties of murine femur and vertebrae. A total of 120 femurs and 180 vertebral bodies (L3-L5) underwent non-destructive cyclic loading to assess their viscoelastic properties followed by mono-cyclic loading to failure to assess their elastic properties. All specimens underwent re-hydration in 0.9% saline for 30min prior to mechanical testing. Analysis indicated that stiffness, modulus of elasticity, yield load, yield strength, ultimate load and ultimate strength of frozen and formalin-fixed femurs and vertebrae were not different from fresh specimens. Cyclic loading of both femurs and vertebrae indicated that loss, storage and dynamic moduli were not affected by freezing. However, formalin fixation altered their viscoelastic properties. Our findings suggest that freezing and formalin fixation over a 2-week period do not alter the elastic mechanical properties of murine femurs and vertebrae, provided that specimens are re-hydrated for at least half an hour prior to testing. However, formalin fixation weakened the viscoelastic properties of murine bone by reducing its ability to dissipate viscous energy. Future studies should address the long-term effects of both formalin fixation and freezing on the mechanical properties of murine bone.
小鼠骨骼标本在骨骼研究中被广泛用于评估环境、生理和病理因素对其力学性能的影响。鉴于力学测试具有破坏性,通常将其作为终末程序进行,在此过程中必须在不影响标本力学性能的情况下对其进行保存。为此,我们旨在研究组织保存(冷冻和福尔马林固定)对小鼠股骨和椎骨弹性及粘弹性力学性能的影响。总共120根股骨和180个椎体(L3-L5)接受了无损循环加载以评估其粘弹性性能,随后进行单循环加载直至破坏以评估其弹性性能。所有标本在力学测试前均在0.9%盐水中复水30分钟。分析表明,冷冻和福尔马林固定的股骨和椎体的刚度、弹性模量、屈服载荷、屈服强度、极限载荷和极限强度与新鲜标本无异。股骨和椎体的循环加载表明,损耗模量、储能模量和动态模量不受冷冻影响。然而,福尔马林固定改变了它们的粘弹性性能。我们的研究结果表明,在两周时间内,冷冻和福尔马林固定不会改变小鼠股骨和椎体的弹性力学性能,前提是标本在测试前至少复水半小时。然而,福尔马林固定通过降低小鼠骨骼耗散粘性能量的能力而削弱了其粘弹性性能。未来的研究应探讨福尔马林固定和冷冻对小鼠骨骼力学性能的长期影响。