Akbarshahi Massoud, Fernandez Justin W, Schache Anthony G, Pandy Marcus G
Department of Mechanical Engineering, University of Melbourne, Victoria 3010, Australia.
Auckland Bioengineering Institute, University of Auckland, Auckland 1010, New Zealand; Department of Engineering Science, University of Auckland, Auckland 1010, New Zealand.
Med Eng Phys. 2014 Sep;36(9):1122-33. doi: 10.1016/j.medengphy.2014.06.009. Epub 2014 Jul 3.
Patellofemoral joint pain is a common problem experienced by active adults. However, relatively little is known about patellofemoral joint load and its distribution across the medial and lateral facets of the patella. In this study, biomechanical experiments and computational modeling were used to study patellofemoral contact mechanics in four healthy adults during stair ambulation. Subject-specific anatomical and gait data were recorded using magnetic resonance imaging, dynamic X-ray fluoroscopy, video motion capture, and multiple force platforms. From these data, in vivo tibiofemoral joint kinematics and knee muscle forces were computed and then applied to a deformable finite-element model of the patellofemoral joint. The contact force acting on the lateral facet of the patella was 4-6 times higher than that acting on the medial facet. The peak average patellofemoral contact stresses were 8.2±1.0 MPa and 5.9±1.3 MPa for the lateral and medial patellar facets, respectively. Peak normal compressive stress and peak octahedral shear stress occurred near toe-off of the contralateral leg and were higher on the lateral facet than the medial facet; furthermore, the peak compressive stress (11.5±3.0 MPa) was higher than the peak octahedral shear stress (5.2±0.9 MPa). The dominant stress pattern on the lateral patellar facet corresponded well to the location of maximum cartilage thickness. Higher loading of the lateral facet is also consistent with the clinical observation that the lateral compartment of the patellofemoral joint is more prone to osteoarthritis than the medial compartment. Predicted cartilage contact stress maps near contralateral toe-off showed three distinctly different patterns: peak stresses located on the lateral patellar facet; peak stresses located centrally between the medial and lateral patellar facets; and peak stresses located superiorly on both the medial and lateral patellar facets.
髌股关节疼痛是活跃成年人常遇到的问题。然而，对于髌股关节负荷及其在髌骨内外侧小平面上的分布了解相对较少。在本研究中，采用生物力学实验和计算建模方法，研究了四名健康成年人在上下楼梯行走过程中的髌股关节接触力学。使用磁共振成像、动态X射线透视、视频动作捕捉和多个测力平台记录了个体特异性的解剖和步态数据。根据这些数据，计算了体内胫股关节运动学和膝关节肌肉力量，然后将其应用于髌股关节的可变形有限元模型。作用于髌骨外侧小平面的接触力比作用于内侧小平面的接触力高4至6倍。髌骨外侧和内侧小平面的平均髌股接触应力峰值分别为8.2±1.0MPa和5.9±1.3MPa。峰值法向压应力和峰值八面体剪应力出现在对侧腿离地时，且外侧小平面上的应力高于内侧小平面；此外，峰值压应力（11.5±3.0MPa）高于峰值八面体剪应力（5.2±0.9MPa）。髌骨外侧小平面上的主要应力模式与最大软骨厚度的位置非常吻合。外侧小平面上更高的负荷也与临床观察结果一致，即髌股关节外侧间室比内侧间室更容易患骨关节炎。对侧腿离地时预测的软骨接触应力图显示出三种明显不同模式：峰值应力位于髌骨外侧小平面；峰值应力位于髌骨内外侧小平面之间的中央；峰值应力位于髌骨内外侧小平面的上方。
