不同颈椎间盘手术对邻近下位椎间孔影响的生物力学研究

目的探讨C5、6人工椎间盘置换、椎间盘摘除、前路椎间融合内固定后对邻近下位椎间孔形态改变的影响,为临床应用颈人工椎间盘置换提供理论依据。方法新鲜成人尸体颈椎标本11具,标本节段包括C3～T1椎体及其椎间盘。11具标本按测试先后顺序分成C5、6完整组、髓核摘除组、置换组及椎间融合内固定组,在0.75、1.50 Nm载荷下测量前屈和后伸状态邻近下位椎间孔高度、宽度的改变,并比较加载前后组内及组间的变化范围（range of variety,ROV）。结果各组颈椎标本在0.75 Nm和1.50 Nm前屈下,C6、7的椎间孔高度、宽度明显增加,在后伸下显著下降,且差异均有统计学意义（P〈0.01）。各组在0.75、1.50 Nm两级载荷下,组内比较位移变化明显,差异有统计学意义（P〈0.01）。在两种负载下,完整组、髓核摘除组与置换组在前屈和后伸状态下,组间两两比较邻近下位椎间孔高度和宽度ROV差异无统计学意义（P〉0.05）;融合组明显高于其余3组,且差异有统计学意义（P〈0.05）。在两种载荷的同组和同状态下,高度和宽度ROV比较差异均有统计学意义（P〈0.01）。结论实验初步证明颈人工椎间盘置换符合颈椎正常的生物力学要求;颈椎间孔屈曲时增大,后伸时减小;椎间融合可能是引起颈椎退变和/或退变加速的原因之一,亦可能是神经根型颈椎病和椎孔外臂丛神经卡压的原因之一。

BIOMECHANICAL RESEARCH ON MORPHOMETRIC CHANGES IN ADJACENT INFERIOR CERVICAL INTERVERTEBRAL FORAMEN AFTER ARTIFICIAL DISC REPLACEMENT

OBJECTIVE: To explore changes in the height and width of the cervical intervertebral foramina of C6.7 before and after the C5.6 discetomy, the replacement or the anterior intervertebral fusion so as to provide the theoretical basis for the clinical practice. METHODS: Eleven fresh cervical spinal specimens were obtained from young adult cadavers. The specimens of C5.6 were divided into the integrity group, the discectomy group, the artificial disc replacement group, and the intervertebral fusion group. The range of variety (ROV) of the C6.7 intervertebral foramen dimensions (height, width) before and after the loading tests (0.75, 1.50 Nm) were measured in the 4 groups. RESULTS: The C6.7 intervetebral foramen height and width increased significantly during flexion (P < 0.01) but decreased significantly during extension (P < 0.01). There was a significant difference between the two test conditions in each of the 4 groups (P < 0.01). However, in the two test conditions there was no significant difference in ROV of the C6,7 intervetebral foramen height and width during flexion and extension between the integrity group, the discectomy, and the artificial disc replacement group (P > 0.05), but a significant difference in the above changes existed in the intervertebral fusion group when compared with the other 3 groups (P < 0.05). In the same group and under the same conditions, the ROV of the C6.7 intervetebral foramen height and width was significantly different in the two test conditions (P < 0.01). CONCLUSION: The results have indicated that artificial disc replacement can meet the requirements of the normal cervical vitodynamics. The adjacent inferior cervical intervetebral foramen increases during flexion but decreases during extension. The intervertebral fusion is probably one of the causes for the cervical degeneration or the accelerated degeneration and for the cervical spondylotic radiculopathy and the brachial plexus compression.