Koizumi M, Tomita N, Tamai S, Oonishi H, Ikada Y
Department of Orthopaedic Surgery, Nara Medical University, 840 Shijyo-cho, Kashihara, Nara 634, Japan.
J Orthop Sci. 1998;3(6):330-5. doi: 10.1007/s007760050061.
Subsurface cracks that had formed in polyethylene artificial knee components were observed nondestructively with a new method, scanning acoustic tomography (SAT). Standardization of the SAT observation was done by in-vitro rolling fatigue testing on an unimplanted ultra high molecular weight polyethylene (UHMWPE) knee component. Retrieved knee components were of two types; KOM (Kyocera, Kyoto, Japan) sterilized with ethylene oxide gas, and MG (Zimmer, IN, USA) sterilized with gamma-irradiation. The SAT images revealed cracks in all the retrieved components, and these existed mainly 0. 3-1.0 mm from the surface. Comparison of crack formation in each portion of the contact area of the polyethylene components showed that the middle portion of the MG type had the highest concentration of cracks. When the distribution of compressive stress on the polyethylene components was assessed by mechanical testing, the strongest compressive stress was seen in the middle portion of MG type components.
采用一种新方法——扫描声学断层扫描（SAT）对聚乙烯人工膝关节部件中形成的亚表面裂纹进行了无损观察。通过对未植入的超高分子量聚乙烯（UHMWPE）膝关节部件进行体外滚动疲劳试验，实现了SAT观察的标准化。回收的膝关节部件有两种类型：用环氧乙烷气体灭菌的KOM（日本京瓷公司，京都）和用伽马射线灭菌的MG（美国印第安纳州的捷迈公司）。SAT图像显示所有回收部件中均存在裂纹，且这些裂纹主要存在于距表面0.3 - 1.0毫米处。对聚乙烯部件接触区域各部分裂纹形成情况的比较表明，MG型的中间部分裂纹浓度最高。通过力学测试评估聚乙烯部件上的压应力分布时，在MG型部件的中间部分观察到最强的压应力。
