Crisco J J, Panjabi M M, Dvorak J
Laboratory, Department of Orthopaedics and Rehabiliation, Yale University School of Medicine, New Haven, CT 06510.
J Biomech. 1991;24(7):607-14. doi: 10.1016/0021-9290(91)90293-v.
Although there are seven vertebrae in the human cervical spine, over 50% of the total axial rotation occurs between the first and second vertebrae, at the atlanto-axial joint. Such motion is possible because of the lack of an intervertebral disc and the shape of the articular facets. The limitation of axial rotation, essential because the spinal cord and vertebral arteries cross this joint, is achieved with ligamentous structures, of which the left and right alar ligaments are primary. When one of the alar ligaments was cut in previous tests of human cadaveric spine (n = 10), the axial rotation to both sides significantly increased. This result does not agree with the long-held hypothesis that axial rotation is limited only by the alar on the side opposite rotation. The purpose of this work was to develop a model of the alar ligaments in axial rotation that is consistent with recent experimental observations. This model predicts that both alars must be intact to limit axial rotation; if one alar is injured, the normal mechanism becomes nonfunctional. The model also predicts the observation that a significant percentage of rotation at the atlanto-axial joint occurs freely, without ligamentous resistance. A physical and a mathematical description of the model is presented. Cadaveric experimental data are demonstrated to support the model.
尽管人类颈椎有七块椎骨，但超过50%的轴向旋转发生在第一和第二椎骨之间，即寰枢关节处。这种运动之所以可能，是因为此处没有椎间盘且关节面的形状特殊。由于脊髓和椎动脉穿过该关节，轴向旋转受到限制，这主要通过韧带结构来实现，其中左右翼状韧带起主要作用。在之前对人体尸体脊柱（n = 10）的测试中，当切断其中一条翼状韧带时，向两侧的轴向旋转明显增加。这一结果与长期以来认为轴向旋转仅受旋转对侧翼状韧带限制的假设不一致。这项工作的目的是建立一个与最近实验观察结果一致的轴向旋转时翼状韧带模型。该模型预测，两条翼状韧带都必须完整才能限制轴向旋转；如果其中一条翼状韧带受损，正常机制就会失效。该模型还预测了寰枢关节相当大比例的旋转是自由发生的，没有韧带阻力这一观察结果。文中给出了该模型的物理和数学描述。尸体实验数据被证明支持该模型。
