Tsantrizos Anthony, Ito Keita, Aebi Max, Steffen Thomas
Division of Orthopaedic Surgery, McGill University, Montreal, Canada.
Spine (Phila Pa 1976). 2005 Oct 1;30(19):2129-37. doi: 10.1097/01.brs.0000181052.56604.30.
A biomechanical study investigating the intradiscal mechanics of human lumbar intervertebral discs (IVDs).
To assess the relationship between nucleus pulposus migration and intradiscal strains as a function of degeneration.
Intradiscal deformation studies have documented the nucleus pulposus migration capabilities during bending but without assessing subsequent intradiscal strains of the anulus fibrosus. Degenerated IVDs show higher anular laxity, hypermobility, and, perhaps, segmental instability. It is unknown if nucleus pulposus migration might be the cause of increased intradiscal anular strains and if such a phenomenon is modulated by IVD degeneration.
Eighteen healthy and degenerated IVDs were subjected to compression, extension, flexion, and lateral bending. Craniocaudal radiographs at unloaded and loaded steps documented positions of wires placed within and beads glued to the external surface in the mid-transverse plane. Circumferential and radial strains from the anterior, lateral, and posterolateral regions during load were compared between healthy and degenerated IVDs.
The nucleus pulposus migrated to the opposite side of bending regardless of bending direction and significantly more in degenerated IVDs. The highest nucleus pulposus migration was observed during lateral bending. Circumferential tensile strains were significantly higher in the posterolateral regions of degenerative IVDs during all loads. Degeneration significantly increased radial tensile and compressive strains during all bending loads.
Increased nucleus pulposus migration in degenerated IVDs may result in increased shifting of the IVD pivot point during bending movements as well as intradiscal anular strains, particularly in the posterolateral anulus. This phenomenon may explain the segmental instability observed in degenerated segments as well as the associated anular tears present in the posterolateral region before IVD failure.
一项关于人体腰椎椎间盘（IVD）椎间盘内力学的生物力学研究。
评估髓核迁移与椎间盘内应变之间随退变程度变化的关系。
椎间盘变形研究记录了弯曲过程中髓核的迁移能力，但未评估随后纤维环的椎间盘内应变。退变的椎间盘显示出更高的纤维环松弛度、活动度增加，或许还有节段性不稳定。尚不清楚髓核迁移是否可能是椎间盘内纤维环应变增加的原因，以及这种现象是否受椎间盘退变的调节。
对18个健康和退变的椎间盘进行压缩、伸展、弯曲和侧方弯曲。在未加载和加载步骤时的矢状面X线片记录了置于椎间盘内的金属丝以及粘贴于椎间盘外表面中横平面的珠子的位置。比较健康和退变椎间盘在加载过程中前侧、外侧和后外侧区域的周向和径向应变。
无论弯曲方向如何，髓核均向弯曲的对侧迁移，且在退变的椎间盘中迁移更为明显。在侧方弯曲时观察到髓核迁移最多。在所有载荷下，退变椎间盘后外侧区域的周向拉伸应变均显著更高。退变在所有弯曲载荷下均显著增加了径向拉伸和压缩应变。
退变椎间盘中髓核迁移增加可能导致弯曲运动过程中椎间盘枢轴点的位移增加以及椎间盘内纤维环应变增加，尤其是在后外侧纤维环。这种现象可能解释了退变节段中观察到的节段性不稳定以及在椎间盘失效前在后外侧区域出现的相关纤维环撕裂。
