Influence of gamma-irradiation sterilization and temperature on the fracture toughness of ultra-high-molecular-weight polyethylene
Influence of gamma-irradiation sterilization and temperature on the fracture toughness of ultra-high-molecular-weight polyethylene
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DOI：
10.1016/s0142-9612(96)00207-4
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发表时间：
1997-05-01
期刊：
影响因子：
14
通讯作者：
FitzPatrick, DP
中科院分区：
文献类型：
--
作者：
Pascaud, RS;Evans, WT;FitzPatrick, DP
由医用级超高分子量聚乙烯 (UHMW-PE) 制成的膝关节假体的胫骨平台部件的表面损伤归因于疲劳断裂机制引起的分层磨损。有人提出，诸如部件设计和灭菌方法之类的因素会导致这种失效机制。因此，了解 UHMW-PE 的断裂行为对于优化总关节组件的体内寿命至关重要。因此，在环境温度和体温下，在空气中以 25 kGy 的最小剂量进行伽马射线照射灭菌之前和之后，确定了商业 UHMW-PE 的弹塑性断裂韧性参数 J。延性稳定性理论和实验数据都表明裂纹以稳定的方式扩展，尽管稳定性受到灭菌过程的影响。伽玛射线灭菌导致断裂韧性 J(lc) 损失 50%，撕裂模量 (T-m) 降低 30%。这种大幅降低可能会导致部件的残余强度、使用载荷下的最大允许裂纹尺寸和使用寿命降低 50%（假设存在熔合缺陷等缺陷）。裂纹从原始尺寸发展到最大允许尺寸所需的时间可以减少 30%，从而更早地失效。就关节置换部件的设计而言，需要考虑的关键因素是设计应力水平，考虑到辐照过程，设计应力水平应减半。扫描电子显微镜研究表明，材料在平行于断裂面的层中失效。 (C) 1997 爱思唯尔科学有限公司。
Surface damage of the tibial plateau components of knee prostheses made from medical grade ultrahigh-molecular-weight polyethylene (UHMW-PE) has been attributed to delamination wear caused by a fatigue fracture mechanism. It has been proposed that factors such as component design and method of sterilization contribute to such failure mechanisms. Understanding the fracture behaviour of UHMW-PE is therefore critical in optimizing the in vivo life-span of total joint components. The elastic-plastic fracture toughness parameter J was consequently determined for a commercial UHMW-PE at ambient and body temperatures, before and after gamma-irradiation sterilization in air at a minimum dose of 25 kGy. Both ductile stability theory and experimental data suggest that cracks propagate in a stable manner, although stability is affected by the sterilization process. Sterilization with gamma-irradiation results in a loss in fracture toughness J(lc) of 50% and a decrease in tearing modulus (T-m) of 30%. This dramatic reduction could result in a 50% decrease in the residual strength of the components, maximum permissible crack size under service loading and service life (assuming flaws such as fusion defects exist). The time required for a crack to grow from its original size to the maximum permissible size could be decreased by 30%, resulting in earlier failure. In terms of the design of joint replacement components the critical factor to envisage is the design stress level, which should be halved to account for the irradiation process. A scanning electron microscope study reveals that the material fails in layers parallel to the fracture surface. (C) 1997 Elsevier Science Limited.