Combined wear and ageing of ceramic-on-ceramic bearings in total hip replacement under edge loading conditions
Combined wear and ageing of ceramic-on-ceramic bearings in total hip replacement under edge loading conditions
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DOI：
10.1016/j.jmbbm.2019.05.011
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发表时间：
2019-10-01
影响因子：
3.9
通讯作者：
Jennings, Louise M.
中科院分区：
文献类型：
--
作者：
Al-Hajjar, Mazen;Gremillard, Laurent;Jennings, Louise M.
全髋关节置换术中的陶瓷对陶瓷关节面已显示出在髋关节置换术中提供低磨损解决方案的潜力。评估这些材料的摩擦学性能对于预测其在患者中的长期性能非常重要。在这项研究中，设计了一种方法来评估复合陶瓷在不利的边缘载荷条件和加速老化下的摩擦学体外行为。考虑了两种商业陶瓷复合材料，即氧化铝增韧的氧化锆（ATZ，ceramys（R））和氧化锆增韧的氧化铝（ZTA，symarec（R））。使用利兹Mark II髋关节模拟器对关节面组合进行了总计800万次循环研究，前200万次循环在正常步态下进行（无边缘载荷），随后600万次循环在增加由内外侧分离驱动的边缘载荷条件下进行。每百万次循环，使用高压灭菌器中的加速方案对轴承对进行水热老化。边缘载荷结合老化对ATZ轴承的影响很大，导致磨损条上的整体老化动力学比对照头上的慢。在高压釜老化步骤中，单斜部分在磨损条纹区域上比在未磨损区域上增加更多。因此，这两个结果表明，单斜相被删除在冲击引起的边缘加载。两种材料的磨损性能相似，在这些临床相关不良条件下表现出相对较低的磨损率和较低水平的显微结构损伤。
Ceramic-on-ceramic bearings in total hip replacement have shown the potential to provide low wear solutions in hip replacement. Assessing the tribological performance of these materials is important to predict their long-term performance in patients. In this study, a methodology was devised to assess the tribological in vitro behaviour of composite ceramics under combined adverse edge loading conditions and accelerated ageing. Two commercial ceramic composites were considered, namely Alumina-Toughened Zirconia (ATZ, ceramys (R)) and Zirconia-Toughened Alumina (ZTA, symarec (R)). The bearing couples were studied using the Leeds Mark II hip joint simulator for a total of eight million cycles, the first two million under normal gait (no edge loading) and the following six million cycles with the addition of edge loading conditions driven by medial-lateral separation. The bearing couples underwent hydrothermal ageing using an accelerated protocol in autoclave every million cycles.The influence of edge loading combined with ageing was significant for ATZ bearings, resulting in a slower overall ageing kinetics over the wear stripe than on the control heads. During the autoclave ageing steps, the monoclinic fraction increased more over the wear stripe area than over the unworn area. Both results thus indicated that the monoclinic phase was removed during shocks induced by edge loading. The wear performance of the two materials were similar exhibiting relatively low wear rates and low level of microstructural damage for these clinically relevant adverse conditions.