Edge loading in metal-on-metal hips: low clearance is a new risk factor
Edge loading in metal-on-metal hips: low clearance is a new risk factor
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金属对金属髋部的边缘负载：低间隙是一个新的风险因素
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
P. Cann
中科院分区：
文献类型：
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作者：
R. Underwood;A. Zografos;R. Sayles;A. Hart;P. Cann
大股骨头金属对金属和表面置换髋关节的翻修率明显高于传统全髋关节置换术。这些部件的翻修与边缘载荷引起的高磨损有关;当股骨头-髋臼杯接触面延伸到髋臼杯边缘时，会发生这种情况。目前对此有两种解释;第一，滑液夹带损失导致润滑膜破裂，第二，边缘载荷导致接触压力局部大幅增加，从而导致髋臼杯边缘处的膜厚度减小，这导致磨损增加。提出了一种计算关节反力矢量到杯缘距离的方法--接触斑中心距。然而，边缘加载风险的临界距离是从接触块边缘到边缘的距离（CPER）。对边缘磨损和非边缘磨损髋关节假体的分析表明，CPCR值无统计学差异，但边缘磨损髋关节的CPER值显著较低。低间隙髋关节具有更适形的接触，具有更大直径的接触面，因此对于类似定位的髋关节，边缘载荷的风险更大。
The revision rate of large head metal-on-metal and resurfacing hips are significantly higher than conventional total hip replacements. The revision of these components has been linked to high wear caused by edge loading; which occurs when the head–cup contact patch extends over the cup rim. There are two current explanations for this; first, there is loss of entrainment of synovial fluid resulting in breakdown of the lubricating film and second, edge loading results in a large local increase in contact pressure and consequent film thickness reduction at the cup rim, which causes an increase in wear. This paper develops a method to calculate the distance between the joint reaction force vector and the cup rim – the contact patch centre to rim (CPCR) distance. However, the critical distance for the risk of edge loading is the distance from the contact patch edge to rim (CPER) distance. An analysis of explanted hip components, divided into edge worn and non-edge-worn components showed that there was no statistical difference in CPCR values, but the CPER value was significantly lower for edge worn hips. Low clearance hips, which have a more conformal contact, have a larger diameter contact patch and thus are more at risk of edge loading for similarly positioned hips.