Baker D A, Hastings R S, Pruitt L
Department of Mechanical Engineering, University of California, Berkeley, California 94720, USA.
J Biomed Mater Res. 1999 Sep 15;46(4):573-81. doi: 10.1002/(sici)1097-4636(19990915)46:4<573::aid-jbm16>3.0.co;2-a.
The aim of this work is to understand the role of chemical and radiation induced crosslinking on the fatigue crack propagation resistance of medical grade ultrahigh molecular weight polyethylene (UHMWPE). In recent years, the need to improve the tribological performance of UHMWPE used in total joint replacements has resulted in the widespread utilization of crosslinking as a method to improve wear resistance. Although crosslinking has been shown to drastically improve the wear resistance of the polymer, the potential trade-off in fatigue properties has yet to be addressed. Fatigue crack propagation resistance is a concern in tibial inserts where large cyclic stresses are sufficient to drive the growth of subsurface cracks that potentially contribute to delamination wear mechanisms. For clinical relevance, the combined effects of sterilization and aging are examined in two commercially available crosslinked resins. Nonsterile and unaged resins serve as a control. To evaluate the effect of crosslinking, a comparison is made to uncrosslinked resins. Scanning electron microscopy is used to provide an understanding of fatigue fracture mechanisms in the crosslinked polymers. The results of this study show that the current level of crosslinking used in orthopedic resins for enhanced wear resistance is not beneficial for fatigue crack propagation resistance.
这项工作的目的是了解化学和辐射诱导交联对医用级超高分子量聚乙烯（UHMWPE）抗疲劳裂纹扩展性能的作用。近年来，提高全关节置换中使用的UHMWPE摩擦学性能的需求导致交联作为一种提高耐磨性的方法被广泛应用。虽然交联已被证明能显著提高聚合物的耐磨性，但疲劳性能方面潜在的权衡尚未得到解决。抗疲劳裂纹扩展性能是胫骨植入物中的一个问题，在那里大的循环应力足以驱动表面下裂纹的生长，而这些裂纹可能导致分层磨损机制。为了具有临床相关性，在两种市售的交联树脂中研究了灭菌和老化的综合影响。未灭菌和未老化的树脂作为对照。为了评估交联的效果，将其与未交联的树脂进行比较。使用扫描电子显微镜来了解交联聚合物中的疲劳断裂机制。这项研究的结果表明，目前用于增强耐磨性的骨科树脂中的交联水平对抵抗疲劳裂纹扩展并无益处。
