Nazari Jalil, Pope Malcolm H, Graveling Richard A
School of Health & Nutrition and National Public Health Management Centre, Tabriz University of Medical Science, Tabriz, East Azerbaijan, Iran.
Clin Biomech (Bristol). 2012 Mar;27(3):213-7. doi: 10.1016/j.clinbiomech.2011.09.011. Epub 2011 Oct 20.
Previous studies reported that, in non-degenerate discs, the nucleus pulposus migrates posteriorly during flexion and anteriorly during extension within the intervertebral disc. However, in these studies the differences between anterior and posterior distances have been regarded as an indicator of nucleus pulposus migration. This study investigated the reality of migration of the nucleus pulposus within the intervertebral disc with changing postures.
Magnetic resonance images were obtained of the lumbar spines of 25 asymptomatic volunteers in sitting, standing and supine postures. The anterior and posterior height of the intervertebral disc, the anterior -posterior length of the intervertebral disc and nucleus pulposus, and the positions of the anterior and posterior margins of the nucleus were measured from mid-line sagittal images.
Changing postures altered the anterior and posterior height of the disc and three types of morphological changes, including changes in the anterior -posterior lengths of the intervertebral disc and nucleus pulposus, together with the position of the nucleus in the disc were found. The length of the intervertebral disc and nucleus pulposus changed under the variations in spinal loading caused by posture.
The results of this study indicated that the apparent nucleus pulposus migration within intervertebral disc is actually deformation of the nucleus pulposus length which depends on posture and the magnitude of the load. In other words, adopting different postures deforms the nucleus pulposus and therefore, changes the position of the nucleus pulposus but there is no apparent nucleus pulposus migration within the intervertebral disc.
先前的研究报道，在非退变椎间盘内，髓核在椎间盘内屈曲时向后迁移，伸展时向前迁移。然而，在这些研究中，前后距离的差异被视为髓核迁移的指标。本研究调查了椎间盘内髓核随姿势变化的迁移实际情况。
对25名无症状志愿者的腰椎进行磁共振成像，分别获取其坐姿、站姿和仰卧位的图像。从矢状面中线图像测量椎间盘的前后高度、椎间盘和髓核的前后长度，以及髓核前后边缘的位置。
姿势改变会改变椎间盘的前后高度，发现了三种形态变化，包括椎间盘和髓核前后长度的变化以及髓核在椎间盘中的位置变化。椎间盘和髓核的长度在姿势引起的脊柱负荷变化下发生改变。
本研究结果表明，椎间盘中髓核的明显迁移实际上是髓核长度的变形，这取决于姿势和负荷大小。换句话说，采用不同姿势会使髓核变形，从而改变髓核的位置，但椎间盘中并无明显的髓核迁移。
