BACKGROUND: Lumbar spondylolisthesis is commonly confirmed by using flexion and extension radiographs, and the severity is determined through slip distance and slip angle.OBJECTIVE: To define and demonstrate the presence of "vertical instability" in lumbar spondylolisthesis, and to determine the most useful radiographic views for clinical purposes and analysis of the surgical strategy.METHODS: Lateral and flexion extension radiographs of the lumbosacral spine in 37 patients with spondylolisthesis taken in standing and recumbent positions and under pelvic traction in the prone or supine positions were suitable for analysis. The changes in disc area, intervertebral kyphotic slip angle, and amount of anteroposterior shift (olisthesis) were measured from the radiographs using a computer digitizer.RESULTS AND CONCLUSION: Maximum slip angle, maximum olisthesis, and minimum normalized disc area were found in patients under erect flexion. Conversely, prone traction and recumbent extension produced minimum slip angle, whereas the lowest anteroposterior shifts were seen in patients under prone and supine traction. Prone traction also resulted in a significantly larger normalized disc area than any other posture. The change in kyphotic slip angle between erect flexion and prone traction was correlated with the change in normalized olisthesis and disc area. Erect flexion and prone traction radiographs represent the extremes of subluxation and reduction of the olisthesis, respectively, and the change in olisthesis seen between these extremes is correlated with the change in disc area and the intervertebral slip angle. Vertical laxity of the affected functional spinal unit resulting from disc degeneration produces laxity in the ligaments and disc anulus, allowing olisthetic motion. Restoration of disc height in turn restores tension to the soft tissues around the disc and results in a spontaneous reduction of the subluxation. Restoration and maintenance of disc height with a spacer or interbody fusion therefore is recommended as a goal in the treatment of spondylolisthesis. When spondylolytic spondylolisthesis involves a posterior column deficiency, additional reconstruction of this column with posterior instrumentation is recommended.%背景:腰椎滑脱一般通过影像学屈伸位片进行确认,通常用滑移距离和滑脱角表明滑脱的严重程度.目的:复制腰椎滑脱中的垂直失稳模式,寻求有效的影像学评价方式.方法:纳入37例腰椎滑脱患者,分别拍直立位、侧卧位、仰卧牵引位、俯卧牵引位腰骶段侧位X射线片.分别在X射线平片上测量间盘面积、滑脱角、滑移距离变化.结果与结论:在患者直立屈曲位片上可测量最大滑脱角、最大滑移距离百分比、最小的间盘面积百分比.俯卧牵引位和侧卧伸展位可测量最小滑脱角,仰卧和俯卧牵引位可测量最小滑移百分比.与其他体位相比俯卧牵引位下的间盘面积百分比最大.直立屈曲位和俯卧牵引位下滑脱角的变化与滑脱节段间盘面积百分比有关.直立屈曲位和俯卧牵引位分别复制了滑脱最严重的程度和复位最大程度.滑移距离的变化与间盘面积和滑脱角的变化有关,节段的垂直失稳是因间盘退变导致韧带和间盘纤维环松弛所致.间盘高度及周围软组织张力的恢复可使滑脱节段自动复位.因此可用植入椎间融合器或骨块行椎间融合治疗腰椎滑脱.峡部裂型滑脱因后柱成分缺失,可行后路椎弓根螺钉固定重建.
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