Liu-Barba David, Hull M L, Howell S M
Biomedical Engineering Graduate Group, University of California, One Shields Avenue, Davis, CA 95616, USA.
J Biomech Eng. 2007 Dec;129(6):818-24. doi: 10.1115/1.2800762.
Knowledge of the coupled motions, which develop under compressive loading of the knee, is useful to determine which degrees of freedom should be included in the study of tibiofemoral contact and also to understand the role of the anterior cruciate ligament (ACL) in coupled motions. The objectives of this study were to measure the coupled motions of the intact knee and ACL-deficient knee under compression and to compare the coupled motions of the ACL-deficient knee with those of the intact knee. Ten intact cadaveric knees were tested by applying a 1600 N compressive load and measuring coupled internal-external and varus-valgus rotations and anterior-posterior and medial-lateral translations at 0 deg, 15 deg, and 30 deg of flexion. Compressive loads were applied along the functional axis of axial rotation, which coincides approximately with the mechanical axis of the tibia. The ACL was excised and the knees were tested again. In the intact knee, the peak coupled motions were 3.8 deg internal rotation at 0 deg flexion changing to -4.9 deg external rotation at 30 deg of flexion, 1.4 deg of varus rotation at 0 deg flexion changing to -1.9 deg valgus rotation at 30 deg of flexion, 1.4 mm of medial translation at 0 deg flexion increasing to 2.3 mm at 30 deg of flexion, and 5.3 mm of anterior translation at 0 deg flexion increasing to 10.2 mm at 30 deg of flexion. All changes in the peak coupled motions from 0 deg to 30 deg flexion were statistically significant (p<0.05). In ACL-deficient knees, there was a strong trend (marginally not significant, p=0.07) toward greater anterior translation (12.7 mm) than that in intact knees (8.0 mm), whereas coupled motions in the other degrees of freedom were comparable. Because the coupled motions in all four degrees of freedom in the intact knee and ACL-deficient knee are sufficiently large to substantially affect the tibiofemoral contact area, all degrees of freedom should be included when either developing mathematical models or designing mechanical testing equipment for study of tibiofemoral contact. The increase in coupled anterior translation in ACL-deficient knees indicates the important role played by the ACL in constraining anterior translation during compressive loading.
了解膝关节在压缩载荷下产生的耦合运动，有助于确定在胫股关节接触研究中应纳入哪些自由度，也有助于理解前交叉韧带（ACL）在耦合运动中的作用。本研究的目的是测量完整膝关节和ACL缺失膝关节在压缩状态下的耦合运动，并比较ACL缺失膝关节与完整膝关节的耦合运动。对10个完整的尸体膝关节施加1600 N的压缩载荷，并测量在0度、15度和30度屈曲时的耦合内外旋转、内翻-外翻旋转以及前后和内外平移。压缩载荷沿着轴向旋转的功能轴施加，该轴大致与胫骨的机械轴重合。切除ACL后再次对膝关节进行测试。在完整膝关节中，耦合运动的峰值为：0度屈曲时3.8度内旋，30度屈曲时变为-4.9度外旋；0度屈曲时1.4度内翻旋转，30度屈曲时变为-1.9度外翻旋转；0度屈曲时1.4 mm的内向平移，30度屈曲时增加到2.3 mm；0度屈曲时5.3 mm的前向平移，30度屈曲时增加到10.2 mm。从0度到30度屈曲，耦合运动峰值的所有变化均具有统计学意义（p<0.05）。在ACL缺失的膝关节中，存在一种强烈趋势（边缘不显著，p=0.07），即前向平移（12.7 mm）比完整膝关节（8.0 mm）更大，而其他自由度的耦合运动相当。由于完整膝关节和ACL缺失膝关节在所有四个自由度上的耦合运动都足够大，足以显著影响胫股关节接触面积，因此在开发数学模型或设计用于研究胫股关节接触的机械测试设备时，应纳入所有自由度。ACL缺失膝关节中耦合前向平移的增加表明ACL在压缩载荷期间限制前向平移中发挥的重要作用。
