AAOS2013：动静态脊柱滑脱的影像学分析

引言：椎管狭窄的患者如果合并脊柱滑脱，在行神经减压术的同时往往需要进行融合手术。评估脊柱滑脱常用X线平片，尽管屈伸位X线片已被推荐用于滑脱的诊断，但对其术前评估作用的价值尚未得到共识。如能结合MRI资料，可能能够更好地对脊柱滑脱患者的特性进行评估。以往的文献往往仅对“动态”或“静态”脊柱滑脱中的一种进行讨论，本研究的目的是应用MRI结合屈伸位X线平片对“动态”和“静态”脊柱滑脱的影像学特点进行分析。

方法：2009-2011年，对在同一医疗单位因脊柱滑脱进行择期初次腰椎后路融合手术的患者进行研究，所有这些患者均在术前进行了MRI和屈伸位平片检查。参考以往的方法通过平片确定滑脱程度并定义“动态”或“静态”滑脱，对轴位、矢状位T2 MRI图像进行评价，分析小关节间液体（FF），小关节囊肿（FC），棘突间液体（ISF）及小关节肥大（FH）的情况。然后对平片判定的动静态不稳和MRI发现的影像学特征进行统计学分析。

结果：共有90例患者被纳入研究，包括114个滑脱节段，患者平均年龄为66.7岁（42.7-85.8岁），在屈伸位平片上有超过3m不稳者更易合并小关节间液体（p=0.018）和棘突间液体（p<0.001）；不稳超过3mm的患者中，39.5%在矢状位MRI上并未表现出脊柱滑脱；如果在MRI图像上发现棘突间液体，其对屈伸位平片超过3mm不稳的阳性预测值（PPV）为69.0%。MRI图像上小关节间无液体对于屈伸位平片上小于3mm的不稳具有75.6%的PPV；MRI存在棘突间液体者中，在平片上发现3mm以上不稳的似然比为3.68；MRI图像上的小关节间液体对不稳的似然比为1.43；36.8%的滑脱患者在仰卧位进行MRI检查时滑脱复位；影像科医师有可能忽略79.2%的小关节间液体（FF），65.5%的小关节囊肿（FC），86.7%的棘突间液体（ISF）；也可能忽略25.4%的MRI图像上的脊柱滑脱。

讨论和结论：MRI图像上的小关节间液体（FF）和/或棘突间液体（ISF）与平片上超过3mm的不稳相关，对于MRI存在以上表现的患者，腰椎减压术前规划时必须对屈伸位平片进行详细审查，以确定是否需要同时进行融合。

与脊柱相关的拓展阅读：

• Arthritis Care Res：早期强直性脊柱炎患者功能障碍更易受放射学损害影响
• ACR：早期强直性脊柱炎患者功能障碍与放射学损害相关性更强
• 部位不当脊柱手术漏报问题的调查
• Neural Regen Res.：脊柱图像引导放疗有助于保护脊髓神经元
• 刘忠军：多模式镇痛可有效减轻患者脊柱术后疼痛
• 脊柱融合术中采用CT三维图像定位人体放射性量更安全
更多信息请点击：有关脊柱更多资讯

Imaging Characteristics of "Dynamic" versus "Static" Spondylolisthesis
INTRODUCTION
The presence of spondylolisthesis may require a concomitant arthrodesis if a surgical decompression of neural elements is necessary for spinal stenosis. Evaluation for existing spondylolisthesis often requires use of plain radiographs. Although use of flexion/extension radiographs has been advocated, its use for pre-operative planning is inconsistent. With the introduction of the magnetic resonance imaging (MRI), the characteristics of sub-classes of spondylolisthesis may be better defined. Traditionally, the “dynamic” type and “static” type of spondylolisthesis have been lumped into a single group in the literature. The goal of this study is to define the radiographic characteristics of “dynamic” and “static” spondylolisthesis with the use of MRI and flexion/extension radiographs.
METHODS
From 2009-11, patients who underwent elective primary posterior spinal fusion for the diagnosis of spondylolisthesis and also had preoperative lumbar MRI and flexion/extension plain radiographs were studied from a single institution. Plain films were assessed for the degree of spondylolisthesis and were designated “dynamic” or “static,” as defined by historical measures. Axial and sagittal T2 MRIs were evaluated for associated facet fluid (FF), facet cysts (FC), interspinous fluid (ISF) and facet hypertrophy (FH). These finding were then statistically evaluated for associations between dynamic and static spondylolisthesis on flexion/extension radiographs and characteristic MRI findings.
RESULTS
Ninety patients were included in the study with 114 levels examined for spondylolisthesis. The average age of the patients was 66.7 years (range 42.7-85.8). Those with greater than 3 mm of instability on flexion/extension films were more likely to have facet fluid (p=0.018) and interspinous fluid (p<0.001). Of the patients who had a greater than 3 mm of instability, 39.5% did not demonstrate spondylolisthesis on the sagittal MRI reconstruction. If interspinous fluid was present on MRI, there was a positive predictive value (PPV) of 69.0% that there would be greater than 3 mm instability on flexion/extension films. Absence of facet fluid on MRI had a PPV of 75.6% for instability less than 3 mm on flexion/extension films. In the presence of interspinous fluid on MRI, the likelihood ratio (LR) of finding more than 3 mm of instability on flexion/extension films was 3.68. The presence of facet fluid on the MRI had a LR of 1.43 for instability. A total of 36.8% of all spondylolisthesis reduced when supine on MRI. Radiologists failed to comment on FF 79.2%, FC 65.5%, ISF 86.7% of the time, respectively. They also failed to identify spondylolisthesis on 25.4% of all the spondylolisthesis on MRI.
DISCUSSION AND CONCLUSIONS
The presence of FF and/or ISF, is associated with instability greater than 3 mm in flexion/extension radiographs. Any presence of the above findings on the MRI should prompt careful scrutiny of the flexion/extension radiographs for pre-operative planning of lumbar decompression and consideration of concomitant arthrodesis.