Swarts Eric, Kop Alan, Jones Noel, Keogh Cathie, Miller Susan, Yates Piers
Department of Medical Engineering and Physics, Royal Perth Hospital, Wellington St., Perth 6000, Western Australia, Australia.
J Biomed Mater Res A. 2008 Mar 1;84(3):753-60. doi: 10.1002/jbm.a.31497.
Six fractured high nitrogen stainless steel (HNSS), polished, tapered hip stems have been reviewed for analysis. Clinical data suggests that poor proximal support (loosening), varus positioning, and canal morphology are implicated in the failure of these stems. Metallurgical assessment reveals a number of microstructural deficiencies contributing to failure. Of significance is poor grain homogeneity and larger grain size near the surface of the fractured stems. It appears some polished, tapered HNSS stems are at risk when combinations of these clinical and metallurgical features occur. As the control of grain size, microstructural uniformity, and inclusion content are critical for optimum mechanical performance, it is important the manufacturers review processing methods to further minimize the risk of component failure.
已对六个经过抛光、呈锥形的高氮不锈钢（HNSS）骨折髋关节柄进行了分析评估。临床数据表明，近端支撑不足（松动）、内翻位以及髓腔形态与这些柄的失效有关。金相评估揭示了一些导致失效的微观结构缺陷。重要的是，断裂柄表面附近的晶粒均匀性差且晶粒尺寸较大。当这些临床和金相特征同时出现时，一些经过抛光的锥形HNSS柄似乎存在风险。由于晶粒尺寸、微观结构均匀性和夹杂物含量的控制对于最佳机械性能至关重要，因此制造商审查加工方法以进一步降低部件失效风险非常重要。
