Ecole de Technologie Supérieure, Laboratoire de Recherche en Imagerie et Orthopédie, Département de Génie de la Production Automatisée, Université du Québec 1100, Rue Notre-Dame O., Montréal, Québec H3C1K3, Canada.
J Biomed Mater Res B Appl Biomater. 2010 Oct;95(1):1-8. doi: 10.1002/jbm.b.31673.
In cemented total hip arthroplasty (THA), porosity plays a major role in the fatigue failure of bone cement. Stem preheating procedure is known to reduce the stem/cement interfacial porosity. In the literature, no information is available about the effect of such procedure on cement bulk porosity. This study helps to find out if stem preheating can have a beneficial effect on bulk porosity, thus enhancing long-term bone cement integrity. A simplified experimental model of a stem/cement/bone construct of a cemented THA is designed to reproduce the mechanical boundary conditions of polymerizing cement. Effect of stem preheating and polymethylmethacrylate prechilling and mixing method (hand mixed and vacuum mixed) on cement porosity are investigated. Bulk porosity is analysed within three zones across the cement mantle in terms of pore number, pore area, and mean pore size. The results demonstrate that bulk cement porosity is strongly influenced by stem preheating, cement precooling as well as cement composition and mixing method. Stem preheating procedure displaces the porosity away from stem/cement interface toward bone; consequently reducing the pore area within the zone near the stem and increasing it in the middle and bone/cement zone. The most pronounced beneficial effect of stem preheating before implantation is visible for vacuum mixed procedure as the cement contains few pores of very small size (<100 μm). However, if stem is preheated, cement precooling should be avoided as it could counteract the beneficial effect of reduced porosity inside cement mantle.
在骨水泥全髋关节置换术（THA）中，孔隙率在骨水泥的疲劳失效中起着重要作用。众所周知，对假体进行预加热处理可以减少假体/骨水泥界面的孔隙率。但目前尚不清楚这种处理方法是否会对骨水泥的整体孔隙率产生影响。本研究旨在探讨假体预加热是否会对骨水泥的整体孔隙率产生有益影响，从而提高骨水泥的长期完整性。本研究设计了一个简化的骨水泥全髋关节假体/骨水泥/骨模型实验，以模拟聚合骨水泥的力学边界条件。研究了假体预加热、聚甲基丙烯酸甲酯预冷以及混合方法（手工混合和真空混合）对骨水泥孔隙率的影响。从孔隙数量、孔隙面积和平均孔径三个方面分析了骨水泥套不同区域的整体孔隙率。结果表明，骨水泥的整体孔隙率受到假体预加热、骨水泥预冷以及骨水泥成分和混合方法的强烈影响。假体预加热将孔隙率从假体/骨水泥界面转移到骨组织中，从而减少了靠近假体区域的孔隙面积，并增加了中间和骨/骨水泥区域的孔隙面积。在植入前对假体进行预加热，对真空混合法的效果最为明显，因为骨水泥中只有少量非常小尺寸（<100μm）的孔隙。然而，如果对假体进行预加热，应避免骨水泥预冷，因为这可能会抵消骨水泥套中孔隙率降低的有益效果。
