A PLANAR MODEL OF THE KNEE-JOINT TO CHARACTERIZE THE KNEE EXTENSOR MECHANISM
A PLANAR MODEL OF THE KNEE-JOINT TO CHARACTERIZE THE KNEE EXTENSOR MECHANISM
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DOI：
10.1016/0021-9290(89)90179-6
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发表时间：
1989-01-01
影响因子：
2.4
通讯作者：
ZAJAC, FE
中科院分区：
文献类型：
--
作者：
YAMAGUCHI, GT;ZAJAC, FE
建立了膝关节的平面静力学模型，计算了股四头肌的有效力臂。选择瞬时旋转中心的路径，以提供股骨相对于胫骨的真实方向。使用该模型，对于从0 °（完全伸展）到90 °的膝关节屈曲角度，以零度增量求解非线性力和力矩平衡方程，产生相对于胫骨插入点和胫股接触点的髌骨取向、髌股接触力和髌韧带力和方向。从这个二维模型的计算机导出的结果同意从以前开发的更复杂的模型从实验获得的数据的结果。然而，由于我们的模型简单，髌骨机制作为杠杆和垫片的操作被清楚地说明。具体地说，发现髌骨的厚度仅在低于35 °的屈曲时显著增加有效力臂。即使实际的力臂在整个屈曲范围内表现出增加。延长髌骨或髌骨韧带改变了从股四头肌传递到髌骨韧带的力，显著增加了屈曲大于25 °时的有效力矩臂。我们的结论是：髌骨的勒韦林作用是膝关节在中到高屈曲角手术的一个基本机制。
A simple planar static model of the knee joint was developed to calculate effective moment arms for the quadriceps muscle. A pathway for the instantaneous center of rotation was chosen that gives realistic orientations of the femur relative to the tibia. Using the model, nonlinear force and moment equilibrium equations were solved at none degree increments for knee flexion angles from 0 (full extension) to 90.degree., yielding patellar orientation, patellofemoral contact force and patellar ligament force and direction with respect to both the tibial insertion point and the tibiofemoral contact point. The computer-derived results from this two-dimensional model agree with results from more complex models developed previously from experimentaly obtained data. Due to our model''s simplicity, however, the operation of the patellar mechanism as a lever as well as a spacer is clearly illustrated. Specifically, the thickness of the patella was found to increase the effective moment arm significantly only at flexions below 35.degree. even though the actual moment arm exhibited an increase throughout the flexion range. Lengthening either the patella or the patellar ligament altered the force transmitted from the quadriceps to the patellar ligament, significantly increasing the effective moment arm at flexions greater than 25.degree.. We conclude that the levering action of the patella is an essential mechanism of knee joint operation at moderate to high flexion angles.