Davies J P, Harris W H
Orthopaedic Biomechanics Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston 02114.
Clin Mater. 1993;12(2):121-6. doi: 10.1016/0267-6605(93)90061-b.
Radiographic follow-up studies of cemented total hip arthroplasty have shown that failure of the cement-metal interface of the femoral component is as high as 25% at 10 years. Recent analyses of clinically successful cemented femoral components obtained in toto with the surrounding cement and femurs after many years of in-vivo service have suggested that the mechanism of the initiation of failure of fixation of cemented femoral components is debonding at the cement-metal interface. Since this critical interface is subjected primarily to cyclic loading, the evaluation of different surface preparations should be studied in fatigue, not static testing. In the current study, several contemporary methods for increasing the strength of the cement-metal interface were evaluated by testing the interfacial fatigue pushout strength under varying conditions of cyclic loading. The effect of a smooth 'implant finish' surface, a surface coated with polymethylmethacrylate (PMMA precoated surface), a combination of a textured surface with PMMA precoat, and a porous titanium mesh coated surface were examined. Precoating the metal with a thin film of PMMA significantly increased the number of compressive fatigue loading cycles required for failure of the cement-metal interface under cyclic loading compared to a smooth, uncoated surface. Adding indentations to the surface and then precoating with PMMA further significantly increased the fatigue life of the cement-metal interface. The strongest interface in fatigue was the titanium fibermesh-cement interface.
骨水泥型全髋关节置换术的影像学随访研究表明，股骨部件的骨水泥-金属界面在10年时的失败率高达25%。最近对多年体内使用后完整取出的临床成功的骨水泥型股骨部件及其周围骨水泥和股骨进行的分析表明，骨水泥型股骨部件固定失败的起始机制是骨水泥-金属界面的脱粘。由于这个关键界面主要承受循环载荷，因此应在疲劳试验而非静态试验中研究不同表面处理方法。在本研究中，通过在不同循环载荷条件下测试界面疲劳推出强度，评估了几种提高骨水泥-金属界面强度的当代方法。研究了光滑的“植入物表面处理”表面、涂有聚甲基丙烯酸甲酯的表面（PMMA预涂表面）、有纹理表面与PMMA预涂相结合的表面以及多孔钛网涂层表面的效果。与光滑的未涂层表面相比，用PMMA薄膜预涂金属显著增加了循环载荷下骨水泥-金属界面失效所需的压缩疲劳加载循环次数。在表面添加凹痕然后用PMMA预涂进一步显著提高了骨水泥-金属界面的疲劳寿命。疲劳强度最高的界面是钛纤维网-骨水泥界面。
