Weinhoffer S L, Guyer R D, Herbert M, Griffith S L
Texas Back Institute Research Foundation, Plano, USA.
Spine (Phila Pa 1976). 1995 Mar 1;20(5):526-31. doi: 10.1097/00007632-199503010-00004.
An in vitro study to determine the intradiscal pressure changes during flexion in levels above a simulated fusion was performed.
To determine if intradiscal pressure increases more during flexion in discs above an instrumented spinal segment compared to an uninstrumented segment.
The progressive degeneration of intervertebral discs adjacent to a fused or fixed segment is a phenomenon that is noted but poorly understood. Intuitively, the degeneration appears to be a function of altered biomechanics of the motion segments in the spine.
Two intervertebral disc levels were evaluated, L3-L4 and L4-L5 from each of six fresh frozen cadaver spines. Pressure measurements were taken with the spine uninstrumented, with bilateral pedicle screw-rod instrumentation from L5 to S1, and with bilateral pedicle screw-rod instrumentation from L4 to S1. Pressure measurements were accomplished with Millar Mikro-Tip pressure transducers. The transducers were placed within the nucleus pulposus of L3-L4 and L4-L5 intervertebral discs. Pressure data were recorded by computer data acquisition. The pressure data were compared by intervertebral level and by the effects of added instrumentation.
In general, the addition of instrumentation significantly affected the intradiscal pressure in the levels above a simulated fusion. The intradiscal pressure increased as the amount of levels involved in the simulated fusion increased. The intradiscal pressure increased as flexion motion increased. A greater increase was seen at the L4-L5 level than the L3-L4 level. When L5-S1 fixation was added, the intradiscal pressure increased. When L4-S1 fixation was added, the intradiscal pressure further increased.
This study demonstrated increasing intradiscal pressures during flexion.
进行了一项体外研究，以确定模拟融合上方节段在屈曲过程中的椎间盘内压力变化。
确定与未植入器械的节段相比，在植入器械的脊柱节段上方的椎间盘在屈曲过程中椎间盘内压力是否增加得更多。
与融合或固定节段相邻的椎间盘进行性退变是一种已被注意到但了解甚少的现象。直观地说，这种退变似乎是脊柱运动节段生物力学改变的结果。
对6具新鲜冷冻尸体脊柱中的每具脊柱的L3-L4和L4-L5两个椎间盘节段进行评估。在脊柱未植入器械、从L5至S1进行双侧椎弓根螺钉-棒器械植入以及从L4至S1进行双侧椎弓根螺钉-棒器械植入的情况下进行压力测量。使用Millar Mikro-Tip压力传感器完成压力测量。将传感器放置在L3-L4和L4-L5椎间盘的髓核内。通过计算机数据采集记录压力数据。通过椎间盘节段以及额外器械植入的影响对压力数据进行比较。
一般来说，器械植入显著影响模拟融合上方节段的椎间盘内压力。随着模拟融合所涉及节段数量的增加，椎间盘内压力升高。随着屈曲运动增加，椎间盘内压力升高。在L4-L5节段比L3-L4节段观察到更大的压力升高。当增加L5-S1固定时，椎间盘内压力升高。当增加L4-S1固定时，椎间盘内压力进一步升高。
本研究表明屈曲过程中椎间盘内压力增加。
