下腰椎椎间孔形态与椎间盘高度丢失的相关性研究

Experimental study of correlation between morphological characteristics of the intervertebral foramina and disc heights in low lumbar spine

目的描述下腰椎椎间孔的形态及椎间盘高度丢失时椎间孔形态的变化。方法取正常的成年新鲜尸体下腰椎标本8具(L3～S1),观察标本在不同状态(椎间盘完整和椎间盘破坏)及不同加载条件(0、300、500N)下L4,5 和L5S1椎间孔的形态及其和神经根的解剖关系,测量椎间孔的高度、最大宽度、最小宽度,于X线侧位片上测量椎间盘前、后高度。结果在未加载的自然状态下,椎间孔上大下小,呈倒置的泪滴形,神经根位于椎间孔上部。在椎间盘完整的状态下,加载500N时,椎间孔形态及其与神经根关系的变化不明显。摘除髓核,随着加载量逐渐增大,椎间孔逐渐缩小、变形,神经根被推挤向同位椎弓根的下缘;椎间孔高度、最大宽度和椎间盘前高、后高逐渐减小,与未加载时比较差异有显著性(P<0.05)。经多元线性回归分析,椎间孔高度与椎间盘后高、前高呈线性相关。结论椎间盘高度丢失与椎间孔形态改变关系密切,椎间孔形态改变增加了神经根卡压的危险性。

Objective To investigate the morphological characteristics of the intervertebral foramina and their alterations in the process of disc height loss in low lumbar spine in order to provide basic data for the diagnosis and treatment of foraminal stenosis. Methods Eight fresh cadaveric lumbar spines of L3 to S1 were obtained for study, which were cleaned off their surrounding muscles and kept the ligaments, annulus fibrous and nerve roots attached. The morphological characteristics of foramina of L4,5 and L5S1 and their anatomic relationships with the nerve roots were observed with and without nucleus pulposus in situ under different loading conditions (0, 300, 500 N). The foraminal dimensions including heights, maximal widths and minimal widths were measured, and the disc heights were measured on lateral radiograph under above loading conditions as well. Results Without any loading, the foramina were inverted teardrop shaped, the foramina of L4,5 were similar to that of L5S1. The nerve roots were located in the upper part of the foramina, and passed across the foramina obliquely. With 500 N loading, the shapes of the foramina and the relationships with the nerve roots were found to be changed little. After removal of nucleus pulposus and more loading was applied, the foramina became stenotic gradually and the nerve roots were pushed against the superior pedicle. The foraminal heights, maximal widths and the anterior, posterior disc heights became narrower, and were significantly different from those under no loading condition (P< 0.05). The foraminal heights had multiple linear correlations with the posterior and the anterior disc heights. Conclusion The shape and dimension of foramina changes as the disc height alters. The foraminal height is significantly correlated with the anterior and the posterior disc height. The alteration of the foraminal morphological characteristics may jeopardize the nerve roots of excessive compression.