Mann Kenneth A, Miller Mark A, Race Amos, Verdonschot Nico
Department of Orthopedic Surgery, SUNY Upstate Medical University, 3216 Institute for Human Performance, 750 East Adams Street, Syracuse, New York 13210, USA.
J Orthop Res. 2009 Mar;27(3):340-6. doi: 10.1002/jor.20777.
Loss of fixation at the cement-bone interface is known to contribute to aseptic loosening, but little is known about the mechanical damage response of this interface. An in vitro study using cement-bone specimens subjected to shear fatigue loading was performed, and the progression of stiffness changes and creep damage at the interface was measured using digital image correlation techniques. Stiffness changes and creep damage were localized to the contact interface between cement and bone. Interface creep damage followed a three-phase response with an initial rapid increase in creep, followed by a steady-state increase, concluding in a final rapid increase in creep. The initial creep phase was accompanied by an increase in interface stiffness, suggesting an initial locking-in effect at the interface. Interface stiffness decreased as creep damage progressed. Power law models were reasonably successful in describing the creep and stiffness damage response and were a function of loading magnitude, number of loading cycles, and contact area at the interface. More microcrack damage occurred to the cement when compared to the bone, and the damage was localized along the interface. These findings indicate that damage to the cement-bone interface could be minimized by improving cement-bone contact and by strengthening the fatigue resistance of the cement.
已知骨水泥与骨界面处的固定丧失会导致无菌性松动，但关于该界面的机械损伤反应却知之甚少。进行了一项体外研究，对承受剪切疲劳载荷的骨水泥-骨标本进行研究，并使用数字图像相关技术测量界面处刚度变化和蠕变损伤的进展情况。刚度变化和蠕变损伤局限于骨水泥与骨之间的接触界面。界面蠕变损伤呈现三相反应，初始阶段蠕变迅速增加，随后是稳态增加，最后蠕变再次迅速增加。初始蠕变阶段伴随着界面刚度的增加，表明界面处存在初始锁定效应。随着蠕变损伤的进展，界面刚度降低。幂律模型在描述蠕变和刚度损伤反应方面相当成功，并且是载荷大小、加载循环次数和界面接触面积的函数。与骨相比，骨水泥出现了更多的微裂纹损伤，且损伤沿界面局部化。这些发现表明，通过改善骨水泥与骨的接触以及增强骨水泥的抗疲劳性，可以将骨水泥-骨界面的损伤降至最低。
