Mimura M
Department of Orthopaedic Surgery, School of Medicine Chiba University, Japan.
Nihon Seikeigeka Gakkai Zasshi. 1990 Jul;64(7):546-59.
The purpose of this study is to investigate the rotational instability of the lumbar spine using bi-plane X-ray analysis system and to clarify mechanical etiology of the lumbar instability. The following results were obtained. (1) The range of rotational motion was about 2 to 3 degrees at each motion segment in the normal lumbar spine. The rotational motion was significantly large in spondylolysis, spondylolisthesis, and degenerative spondylolisthesis. (2) The rotational instability and the flexion-extension instability correlated to each other in spondylolysis and spondylolisthesis. However, in degenerative spondylolisthesis, the rotational instability and the antero-posterior instability were correlated to each other. (3) Instantaneous axis of rotation (IAR) was located at the posterior part of the intervertebral disc in the normal L4 vertebra, and more posteriorly in the L5 vertebra, while the IAR was located anteriorly in spondylolysis, and posteriorly in degenerative spondylolisthesis. (4) When the trunk was twisted, the lumbar lordotic angle was generally decreased, and the lumbar spine showed scoliotic curvature convex to the twisted direction. The apex was located at the L4/5 intervertebral level. Highly significant increases in flexion motion associated with rotation were observed at the pathological levels of spondylolysis and degenerative spondylolisthesis.
本研究的目的是使用双平面X射线分析系统研究腰椎的旋转不稳定性，并阐明腰椎不稳定的力学病因。获得了以下结果。（1）正常腰椎各运动节段的旋转运动范围约为2至3度。在椎弓根峡部裂、腰椎滑脱和退行性腰椎滑脱中，旋转运动明显增大。（2）在椎弓根峡部裂和腰椎滑脱中，旋转不稳定与屈伸不稳定相互关联。然而，在退行性腰椎滑脱中，旋转不稳定与前后不稳定相互关联。（3）正常L4椎体的瞬时旋转轴（IAR）位于椎间盘后部，L5椎体的IAR更靠后，而在椎弓根峡部裂中IAR位于前方，在退行性腰椎滑脱中IAR位于后方。（4）当躯干扭转时，腰椎前凸角通常减小，腰椎呈现向扭转方向凸出的脊柱侧凸。顶点位于L4/5椎间水平。在椎弓根峡部裂和退行性腰椎滑脱的病理水平处，观察到与旋转相关的屈曲运动显著增加。
