Eck Jason C, Humphreys S Craig, Lim Tae-Hong, Jeong Soon Tack, Kim Jesse G, Hodges Scott D, An Howard S
Center for Sports Medicine and Orthopaedics Foundation for Research, Chattanooga, Tennessee, USA.
Spine (Phila Pa 1976). 2002 Nov 15;27(22):2431-4. doi: 10.1097/00007632-200211150-00003.
A biomechanical study was performed using cadaveric cervical spine specimens.
To determine the effect of cervical spine fusion on adjacent-level intradiscal pressure.
Clinical studies have reported that patients with spinal fusion are at greater risk of pathology and early disc degeneration at adjacent levels. It is hypothesized that eliminating motion at one level leads to hypermobility and increased forces at adjacent levels, thus increasing the rate of disc degeneration.
Six cadaveric cervical spine specimens were tested. Specimens were stabilized at T1 and loaded at C3 to 20 degrees of flexion and 15 degrees of extension. Intradiscal pressures and segmental motion at C4-C5 and C6-C7 were recorded first on intact specimens, and then after anterior cervical plating at C5-C6. Changes in intradiscal pressure and segmental motion were calculated and statistically analyzed using a paired Student t test.
Intradiscal pressures were significantly increased during flexion at both adjacent levels. The pressure increased by 73.2% at C4-C5 (P = 0.002), and by 45.3% at C6-C7 (P = 0.006). Intradiscal pressures increased at both adjacent levels during extension, but not significantly. During flexion, segmental motion increased at both adjacent levels, with greater increases at C4-C5. During extension, segmental motion increased at both adjacent levels, with greater increases at C6-C7.
Clinical studies have reported increased rates of disc degeneration at levels adjacent to fusion. It is believed that eliminating motion through fusion shifts the load to the adjacent levels, causing earlier disc degeneration. This study has shown that significant increases in intradiscal pressure and segmental motion occur at levels adjacent to fusion during normal range of motion. These results may partially explain the mechanism of early disc degeneration at levels adjacent to cervical spine fusion.
使用尸体颈椎标本进行生物力学研究。
确定颈椎融合对相邻节段椎间盘内压力的影响。
临床研究报告称，脊柱融合患者在相邻节段发生病变和早期椎间盘退变的风险更高。据推测，一个节段运动的消除会导致相邻节段活动过度和受力增加，从而加快椎间盘退变的速度。
对六个尸体颈椎标本进行测试。标本在T1水平固定，并在C3水平施加20度的前屈和15度的后伸负荷。首先在完整标本上记录C4-C5和C6-C7节段的椎间盘内压力和节段运动，然后在C5-C6节段进行颈椎前路钢板固定后再次记录。使用配对学生t检验计算并统计分析椎间盘内压力和节段运动的变化。
在两个相邻节段的前屈过程中，椎间盘内压力均显著增加。C4-C5节段压力增加了73.2%（P = 0.002），C6-C7节段压力增加了45.3%（P = 0.006）。在两个相邻节段的后伸过程中，椎间盘内压力也增加，但不显著。在前屈过程中，两个相邻节段的节段运动均增加，C4-C5节段增加幅度更大。在后伸过程中，两个相邻节段的节段运动均增加，C6-C7节段增加幅度更大。
临床研究报告称，融合相邻节段的椎间盘退变率增加。据信，通过融合消除运动将负荷转移至相邻节段，导致更早的椎间盘退变。本研究表明，在正常运动范围内，融合相邻节段的椎间盘内压力和节段运动显著增加。这些结果可能部分解释了颈椎融合相邻节段早期椎间盘退变的机制。
