Osti O L, Vernon-Roberts B, Fraser R D
Institute of Medical and Veterinary Science, Royal Adelaide Hospital.
Spine (Phila Pa 1976). 1990 Aug;15(8):762-7. doi: 10.1097/00007632-199008010-00005.
An animal model was developed to test the hypothesis that discrete peripheral tears within the anulus lead to secondary degenerative changes in other disc components. In 21 adult sheep, a cut was made in the left anterolateral anulus of three randomly selected lumbar discs. The cut was parallel and adjacent to the inferior end-plate, and had a controlled depth of 5 mm. This left the inner third of the anulus and the nucleus pulposus intact and closely reproduced the rim Lear lesion described by Schmorl. Animals were randomly allocated to different groups in relation to the length of time interval between operation and death, varying from 1 to 18 months. At death, the lumbar spine was cut into individual joint units and each disc sectioned into six parasagittal slabs. After observation of the slabs under the dissecting microscope, two of the six slabs, the one containing the anulus lesion and a contralateral, were processed for histology. The results of this study suggest that, despite the great care taken at operation to ensure that the inner anulus was left intact, progressive failure of the inner anulus was seen in all sheep and occurred in the majority of discs between 4 and 12 months after the operation. Although the outermost anulus showed the ability to heal, the defect induced by the cut led initially to deformation and bulging of the collagen bundles, and eventually to inner extension of the tear and complete failure. These findings suggest that discrete tears of the outer anulus may have a role in the formation of concentric clefts and in accelerating the development of radiating clefts. Peripheral tears of the anulus fibrosus therefore may play an important role in the degeneration of the intervertebral joint complex.
为了验证椎间盘纤维环内离散的周边撕裂会导致椎间盘其他成分发生继发性退变这一假说，建立了一种动物模型。在21只成年绵羊中，随机选择三个腰椎间盘，在其左前外侧纤维环处做一个切口。该切口与下终板平行且相邻，深度控制为5毫米。这样使纤维环的内三分之一和髓核保持完整，紧密复制了施莫尔描述的边缘利尔氏损伤。根据手术与死亡之间的时间间隔长短，将动物随机分为不同组，时间间隔从1个月到18个月不等。在处死动物时，将腰椎切成单个关节单元，每个椎间盘切成六个矢状旁切片。在解剖显微镜下观察切片后，从六个切片中选取两个，即包含纤维环损伤的切片和对侧切片，进行组织学处理。本研究结果表明，尽管手术时非常小心以确保纤维环内部保持完整，但在所有绵羊中均观察到纤维环内部进行性破坏，且在手术后4至12个月，大多数椎间盘都出现了这种情况。虽然最外层纤维环显示出愈合能力，但切口引起的缺损最初导致胶原束变形和膨出，最终导致撕裂向内扩展并完全破坏。这些发现表明，纤维环外层的离散撕裂可能在同心裂隙的形成以及加速放射状裂隙的发展中起作用。因此，纤维环周边撕裂可能在椎间关节复合体退变中起重要作用。
