Maurel N, Diop A, Grimberg J
Equipe-Projet Biomécanique et Remodelage Osseux, Ecole Nationale Supérieure d'Arts et Métiers, 151 Boulevard de l'Hôpital, 75013 Paris, France.
J Biomech. 2005 Sep;38(9):1865-72. doi: 10.1016/j.jbiomech.2004.08.019.
In order to help to understand the loosening phenomenon around glenoïd prostheses, a 3D finite element model of a previously tested implanted scapula has been developed. The construction of the model was done using CT scans of the tested scapula. Different bone material properties were tested and shell elements or 8 nodes hexaedric elements were used to model the cortical bone. Surface contact elements were introduced on one hand between the bone and the lower part of the plate of the implant, and on the other, between the loading metallic ball and the upper surface of the implant. The results of the model were compared with those issued from in vitro experiments carried out on the same scapula. The evaluation of the model was done for nine cases of loading of 500 N distributed on the implant, in terms of strains (principal strains of six spots around peripheral cortex of the glenoïd) and displacement of four points positioned on the implant. The best configuration of the model presented here, fits with experiments for most of the strains (difference lower than 150microdef) but it seems to be still too stiff (mainly in the lower part). Nevertheless, we want, in this paper, to underline the importance of doing a multiparametric validation for such a model. Indeed, some models can give correct results for one case of loading but bad results for another kind of loading, some others can give good results for one kind of compared parameters (like strains for instance) but bad results for the other one (like displacements).
为了有助于理解肩胛盂假体周围的松动现象，已开发出一个先前测试过的植入肩胛骨的三维有限元模型。该模型的构建是使用测试肩胛骨的CT扫描完成的。测试了不同的骨材料属性，并使用壳单元或8节点六面体单元对皮质骨进行建模。一方面，在骨与植入物钢板的下部之间引入表面接触单元；另一方面，在加载金属球与植入物的上表面之间引入表面接触单元。将该模型的结果与在同一肩胛骨上进行的体外实验结果进行比较。针对分布在植入物上的500 N的九种加载情况，从应变（肩胛盂周围皮质六个点的主应变）和植入物上四个点的位移方面对模型进行评估。这里呈现的模型的最佳配置，对于大多数应变与实验结果相符（差异低于150微变形），但似乎仍然太硬（主要是在下部）。然而，在本文中，我们想强调对这样一个模型进行多参数验证的重要性。确实，一些模型对于一种加载情况能给出正确结果，但对于另一种加载情况则给出错误结果，还有一些模型对于一种比较参数（例如应变）能给出良好结果，但对于另一种参数（例如位移）则给出错误结果。
