Cook S D, Kester M A, Harding A F, Brown T D, Sandborn P M
J Rehabil Res Dev. 1986 Oct;23(4):27-36.
The clinical and metallurigical characteristics of five cast cobalt-chromium-molybdenum alloy femoral hip prostheses which failed in vivo were evaluated. The devices included: two of the Howmedica Muller-Charnley design, two of the Howmedica Charnley design, and one of the Zimmer Aufranc-Turner design. Fractographic analyses demonstrated that the five devices had failed by fatigue which originated on the lateral aspect. Failure occurred after an average in vivo time of 80.4 months (approximately 6.7 years). Only two of the devices had Rockwell hardness values that were within the ASTM specifications for the alloy. Upon metallurgical examination, moderate to severe levels of gas porosity, interdendritic shrinkage, and nonmetallic inclusions were found in all of the devices. As expected, extremely large grain sizes also were observed in the devices examined. These results indicate that the metallurgical flaws and defects associated with the cast cobalt-chromium-molybdenum alloys used in these devices may preclude successful longterm performance and warrant manufacturer's attention.
对五例在体内失效的铸造钴铬钼合金股骨髋关节假体的临床和金相特性进行了评估。这些假体包括：两个Howmedica Muller-Charnley设计的、两个Howmedica Charnley设计的以及一个Zimmer Aufranc-Turner设计的。断口分析表明，这五个假体均因起源于外侧的疲劳而失效。失效发生在平均80.4个月（约6.7年）的体内时间之后。只有两个假体的洛氏硬度值在该合金的ASTM规范范围内。经金相检查，在所有假体中均发现了中度至重度的气孔率、枝晶间收缩和非金属夹杂物。正如预期的那样，在所检查的假体中还观察到了极大的晶粒尺寸。这些结果表明，与这些假体中使用的铸造钴铬钼合金相关的金相缺陷可能会妨碍长期的成功性能，并值得制造商关注。
