The aim of this study was to determine the effect of the posterior ligaments and facet joints on the shear stiffness of lower cervical functional spinal units in anterior, posterior, and lateral shear. Five functional spinal units were loaded in anterior, posterior, and right lateral shear up to 100 N using a custom-designed apparatus in a materials testing machine. Specimens were tested in three conditions: intact, with the posterior ligaments severed, and with the facet joints removed. There was a significant decrease in anterior stiffness in the 20-100 N load range from 186 (range: 98-327) N/mm in the intact condition to 105 (range: 78-142) N/mm in the disc-only condition (p = 0.03). Posterior stiffness between these condition decreased significantly from 134 (range: 92-182) N/mm to 119 (range: 83-181) N/mm (p = 0.03). There was no significant effect of posterior ligament removal on shear stiffness. No significant differences were found in the lateral direction or in the 0-20 N range for any direction. Under a 100-N shear load, the facet joints played a significant role in the stiffness of the cervical spine in the anterior-posterior direction, but not in the lateral direction.

中文翻译：

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下部颈椎的剪切刚度：后继元素损伤的影响。

这项研究的目的是确定后韧带和小关节在前，后和横向剪切对下颈椎功能脊柱单位剪切刚度的影响。在材料测试机中使用定制设计的设备，将五个功能性脊柱单元加载到前，后和右横向剪切力中，直至100N。在以下三个条件下对标本进行了测试：完整，后韧带切断，小关节切除。在20-100 N的载荷范围内，前刚度从完整状态的186（范围：98-327）N / mm降低到仅椎间盘的状态下的105（范围：78-142）N / mm显着降低。 （p ＝ 0.03）。这些条件之间的后劲度从134（范围：92-182）N / mm显着降低到119（范围：83-181）N / mm（p = 0.03）。去除后韧带对剪切刚度没有显着影响。在横向或任何方向的0-20 N范围内均未发现明显差异。在100 N的剪切载荷下，小关节在前后方向上对颈椎的刚度起着重要作用，而在横向方向上不起作用。