Onan O A, Heggeness M H, Hipp J A
Baylor College of Medicine, Institute for Spinal Disorders, Houston, Texas, USA.
Spine (Phila Pa 1976). 1998 Feb 15;23(4):430-9. doi: 10.1097/00007632-199802150-00005.
The stability of motion segments of human cervical spines was sequentially tested as portions of the vertebral anatomy were removed or cut. Isolated, individual facet joints were then similarly studied.
To define the laxity of isolated cervical facet joints and the relative contribution of the different components of the vertebral anatomy to the overall stability of the cervical spine.
Facet joints are known to be important in determining cervical stiffness and mobility. This is the first known study in which the biomechanical behavior of isolated cervical facet joints has been documented.
From five fresh frozen human cervical spines, three C3-C4 and five C5-C6 motion segments were dissected and potted. Rotations and translations in response to 10 bending or twisting moments were recorded by tracking the motion of a testing plate fixed to the superior vertebrae using an articulated arm digitizer. Each motion segment was tested five times, with sequential dissections performed as follows: intact; after removal of the anterior longitudinal ligament intervertebral disc, and posterior longitudinal ligament; after cutting the interspinous ligament; after isolation of the left facet joint; and after isolation of the right facet joint. Each testing sequence involved applying low and high forces 10 cm from the center of the testing plate in each of 10 testing directions. After completion of rotational testing, landmarks on the superior vertebral body and facet joints were digitized to calculate vertebral translations.
Isolated facet joints allowed up to 19 degrees of flexion, 14 degrees of extension, 28 degrees of lateral bending, and 17 degrees of rotation. Coupled motions were less in isolated facet joints compared with those in intact vertebral bodies. Isolated facet joints allowed up to 9 mm of translation between superior and inferior surfaces.
Isolated cervical facet joints are highly mobile in comparison with their motions within the constraints of intact motion segments; gliding motions of the isolated facet to near dislocation is possible before the facet capsule constrains motion. Cervical coupled motions are a result of an intact vertebral ring and a combination of the two facet joints. The vertebral ring with facet joints and capsules all intact is necessary for lateral bending stability and rotational stability in the cervical spine.
随着椎体解剖结构的部分被移除或切断，对人体颈椎运动节段的稳定性进行了连续测试。然后对孤立的单个小关节进行了类似的研究。
确定孤立颈椎小关节的松弛度以及椎体解剖结构不同组成部分对颈椎整体稳定性的相对贡献。
已知小关节在决定颈椎的刚度和活动度方面很重要。这是首次记录孤立颈椎小关节生物力学行为的已知研究。
从五个新鲜冷冻的人体颈椎中，解剖并固定了三个C3 - C4和五个C5 - C6运动节段。通过使用关节臂数字化仪跟踪固定在上位椎体上的测试板的运动，记录对10个弯曲或扭转力矩的旋转和位移。每个运动节段测试五次，依次进行如下解剖：完整状态；去除前纵韧带、椎间盘和后纵韧带后；切断棘间韧带后；分离左侧小关节后；分离右侧小关节后。每个测试序列包括在10个测试方向中的每个方向上，在距测试板中心10厘米处施加低力和高力。旋转测试完成后，对上位椎体和小关节上的标志点进行数字化处理以计算椎体位移。
孤立的小关节允许高达19度的前屈、14度的后伸、28度的侧屈和17度的旋转。与完整椎体相比，孤立小关节中的耦合运动较少。孤立的小关节允许上下表面之间高达9毫米的位移。
与它们在完整运动节段的约束内的运动相比，孤立的颈椎小关节具有高度的活动性；在关节囊限制运动之前，孤立小关节的滑动运动可能接近脱位。颈椎耦合运动是完整椎体环和两个小关节组合的结果。具有完整小关节和关节囊的椎体环对于颈椎的侧屈稳定性和旋转稳定性是必要的。
