Askew M J, Lewis J L
J Biomech Eng. 1981 Nov;103(4):239-45. doi: 10.1115/1.3138287.
A two-dimensional, finite element model of a single-posted, metal, tibial prosthetic component implanted with PMMA in the proximal tibia is developed. The effects upon the stresses at the PMMA-bone interface and in the cancellous bone around the component due to the inclusion in the model of the cortical shell and the heterogeneity and anisotropy of the cancellous bone, are demonstrated. Various lengths of the fixation post are considered. The cortical shell adds support and stiffness to the bone structure, and allows generation of significant stresses proximally. The heterogeneity of the cancellous bone, as assumed here, dictates the form of the stress distributions and the magnitudes and locations of the peak stress values around the post of the component. Peak stress values can occur at locations proximal to the post tip. The anisotrophy of the cancellous bone significantly alters the magnitudes of the stresses. Lower stresses along the post interface and higher stresses beneath the plate of the prosthesis are seen in the anisotropic models. Lengthening of the fixation post reduces stresses proximally, but the effects of post lengthening upon the maximum stress values around the post are highly dependent upon the assumed properties of the cancellous bone.
建立了一个二维有限元模型，该模型模拟了在胫骨近端用聚甲基丙烯酸甲酯（PMMA）植入的单柱金属胫骨假体部件。研究表明，由于在模型中包含皮质骨壳以及松质骨的非均质性和各向异性，会对PMMA-骨界面以及部件周围松质骨中的应力产生影响。考虑了不同长度的固定柱。皮质骨壳为骨结构增加了支撑和刚度，并在近端产生显著应力。这里假设的松质骨非均质性决定了应力分布的形式以及部件柱周围峰值应力值的大小和位置。峰值应力值可能出现在柱尖近端的位置。松质骨的各向异性显著改变了应力大小。在各向异性模型中，可以看到沿柱界面的应力较低，而假体板下方的应力较高。延长固定柱可降低近端应力，但柱延长对柱周围最大应力值的影响在很大程度上取决于假设的松质骨特性。
