Venäläinen Mikko S, Mononen Mika E, Jurvelin Jukka S, Töyräs Juha, Virén Tuomas, Korhonen Rami K
J Biomech Eng. 2014 Dec;136(12):121005. doi: 10.1115/1.4028801.
Mechanical behavior of bone is determined by the structure and intrinsic, local material properties of the tissue. However, previously presented knee joint models for evaluation of stresses and strains in joints generally consider bones as rigid bodies or linearly elastic solid materials. The aim of this study was to estimate how different structural and mechanical properties of bone affect the mechanical response of articular cartilage within a knee joint. Based on a cadaver knee joint, a two-dimensional (2D) finite element (FE) model of a knee joint including bone, cartilage, and meniscus geometries was constructed. Six different computational models with varying properties for cortical, trabecular, and subchondral bone were created, while the biphasic fibril-reinforced properties of cartilage and menisci were kept unaltered. The simplest model included rigid bones, while the most complex model included specific mechanical properties for different bone structures and anatomically accurate trabecular structure. Models with different porosities of trabecular bone were also constructed. All models were exposed to axial loading of 1.9 times body weight within 0.2 s (mimicking typical maximum knee joint forces during gait) while free varus-valgus rotation was allowed and all other rotations and translations were fixed. As compared to results obtained with the rigid bone model, stresses, strains, and pore pressures observed in cartilage decreased depending on the implemented properties of trabecular bone. Greatest changes in these parameters (up to -51% in maximum principal stresses) were observed when the lowest modulus for trabecular bone (measured at the structural level) was used. By increasing the trabecular bone porosity, stresses and strains were reduced substantially in the lateral tibial cartilage, while they remained relatively constant in the medial tibial plateau. The present results highlight the importance of long bones, in particular, their mechanical properties and porosity, in altering and redistributing forces transmitted through the knee joint.
骨骼的力学行为由组织的结构以及内在的局部材料特性决定。然而，先前用于评估关节应力和应变的膝关节模型通常将骨骼视为刚体或线弹性固体材料。本研究的目的是评估骨骼不同的结构和力学特性如何影响膝关节内关节软骨的力学响应。基于一具尸体膝关节，构建了一个包含骨骼、软骨和半月板几何形状的膝关节二维有限元模型。创建了六种不同的计算模型，其皮质骨、小梁骨和软骨下骨的特性各不相同，而软骨和半月板的双相纤维增强特性保持不变。最简单的模型包含刚性骨骼，而最复杂的模型包含不同骨结构的特定力学特性以及解剖学上精确的小梁结构。还构建了具有不同小梁骨孔隙率的模型。所有模型在0.2秒内承受1.9倍体重的轴向载荷（模拟步态期间典型的最大膝关节力），同时允许自由内翻-外翻旋转，而所有其他旋转和平移均固定。与刚性骨模型得到的结果相比，软骨中观察到的应力、应变和孔隙压力根据小梁骨的设定特性而降低。当使用小梁骨最低模量（在结构水平测量）时，这些参数的变化最大（最大主应力高达-51%）。通过增加小梁骨孔隙率，外侧胫骨软骨中的应力和应变大幅降低，而在内侧胫骨平台中它们保持相对恒定。目前的结果突出了长骨，特别是其力学特性和孔隙率，在改变和重新分配通过膝关节传递的力方面的重要性。
