单节段与双节段经椎弓根椎体截骨术重塑强直性脊柱炎重度胸腰椎后凸畸形患者腰椎前凸曲线的效果及术式选择

The efficacy and the selection of single-level and two-level pedicle subtraction osteotomy in the remodeling of lumbar lordosis curvature for patients with severe thoracolumbar kyphosis caused by ankylosing spondylitis

中文关键词:  强直性脊柱炎  重度胸腰椎后凸畸形  经椎弓根椎体截骨术  腰椎前凸曲线

英文关键词:Ankylosing spondylitis  Severe thoracolumbar kyphosis  Pedicle subtraction osteotomy  Lumbar lordosis curvature

中文摘要:

  【摘要】 目的：分析单节段和双节段经椎弓根椎体截骨术（pedicle subtraction osteotomy，PSO）在强直性脊柱炎（ankylosing spondylitis，AS）重度胸腰椎后凸畸形（后凸Cobb角≥80°）患者中重塑其腰椎前凸曲线的效果，探讨两种术式的适应证。方法：回顾性分析68例接受PSO手术治疗的AS重度胸腰椎后凸畸形患者，其中44例接受单节段PSO治疗，24例接受双节段PSO治疗，随访时间为36.50±15.07个月。所有患者均在术前及末次随访时填写Oswestery功能障碍指数（Oswestry disability index，ODI）量表和视觉模拟量表（visual analogue scale，VAS）。测量术前、术后及末次随访时的胸腰椎后凸Cobb角（global kyphosis，GK）、矢状面躯干偏移（sagittal vertical axis，SVA）、胸椎后凸角（thoracic kyphosis，TK）、腰椎前凸角（lumbar lordosis，LL）、骨盆倾斜角（pelvic tilt，PT）和骶骨倾斜角（sacral slope，SS）。将68例分别接受单节段和双节段PSO患者对比分析后，根据患者术后腰椎前凸顶点的位置分为两组，腰椎前凸顶点在L3或L4组（30例），腰椎前凸顶点在L5或其他腰椎组（38例），比较两组腰椎曲线的大小及形态。将良好的腰椎前凸曲线重塑定义为术后腰椎前凸顶点位于L3或L4水平，进一步筛选出30例实现良好的腰椎前凸曲线重塑的患者，再将其分为单节段PSO组（20例）和双节段PSO（10例）组，使用受试者操作特征（receiver-operating characteristic，ROC）曲线确定这两组之间存在显著性差异的术前影像学参数的最佳临界值（cut-off值）。结果：在68例重度胸腰椎后凸畸形患者中，接受单节段PSO组与双节段PSO组患者术后腰椎前凸顶点的分布无显著性差异（P＞0.05），但是双节段PSO组手术时间更长、术中失血更多、固定节段更长（P<0.05）。术后腰椎前凸顶点在L5或其他腰椎组患者术后的LL和SS均显著小于L3或L4组（P<0.001），而两组患者术后的GK、SVA、TK和PT均无显著性差异（P＞0.05）；不同的截骨水平及截骨术式对术后腰椎前凸顶点的分布均无显著影响（P＞0.05）。在30例实现良好的腰椎前凸曲线重塑的患者中，术后除TK外的所有脊柱骨盆参数较术前明显改善，ODI、VAS评分均有明显改善（P<0.05），随访过程中也未见明显的矫正丢失；其中，双节段PSO组术前的GK、SVA和LL明显大于单节段PSO组（P<0.05），其余的术前参数两组比较均无统计学差异（P＞0.05）。ROC曲线分析结果表明，GK的cut-off值为94.50°，SVA的cut-off值为19.35cm，LL的cut-off值为12.00°。单节段PSO组并发症包括2例截骨椎脱位、1例体位性臂丛神经麻痹和1例术中硬脊膜撕裂，双节段PSO组并发症包括2例体位性臂丛神经麻痹、1例截骨椎脱位和1例随访期间内固定棒断裂。结论：单节段和双节段PSO均能为AS重度胸腰椎后凸畸形的患者实现良好的腰椎前凸曲线重塑，术式的选择取决于患者术前后凸畸形的严重程度。对于GK<94.50°、SVA<19.35cm及LL<12.00°的患者，首先考虑单节段PSO以实现良好的腰椎前凸曲线重塑；相反地，对于脊柱矢状位失衡更严重（GK≥94.50°、SVA≥19.35cm及LL≥12.00°）的患者，双节段PSO是重塑良好腰椎前凸曲线的更佳选择。

英文摘要:

  【Abstract】 Objectives: To analyze the remodeling of lumbar lordosis curvature between ankylosing spondylitis(AS) patients with severe thoracolumbar kyphosis(global kyphosis≥80°) who underwent single- or two-level pedicle subtraction osteotomy(PSO), and to determine the indications of single-level PSO and two-level PSO. Methods: 68 patients with AS-related severe thoracolumbar kyphosis were retrospectively studied, including 44 patients underwent single-level PSO and 24 patients two-level PSO. The average follow-up time was 36.50±15.07 months. All the patients filled out the Oswestry disability index(ODI) and the visual analogue scale(VAS) before PSO and at the final follow-up. Radiological parameters including global kyphosis(GK), sagittal vertical axis(SVA), thoracic kyphosis(TK), lumbar lordosis(LL), pelvic tilt(PT) and sacral slope(SS) were measured preoperatively, postoperatively and at the final follow-up. After comparison and analysis, the patients were divided into two groups based on the segment of postoperative apex of lumbar lordosis(LL apex): 30 cases in LL apex at L3 or L4 group and 38 cases in LL apex at L5 or other segments group. Satisfying remodeling of lumbar lordosis curvature was defined as the postoperative LL apex located at L3 or L4. 30 patients achieving satisfying remodeling of lumbar lordosis curvature were further screened out and then divided into single-level PSO group(20 cases) and two-level PSO group(10 cases). Receiver-operating characteristic(ROC) curve was used to find the cut-off value of preoperative parameters that were significantly different between the two groups. Results: In all 68 patients with severe thoracolumbar kyphosis, there was no significant difference in the relocation of LL apex between those underwent single or two-level PSO. However, longer operative time, more intraoperative blood loss and more levels of instruments were observed in those who underwent two-level PSO(P<0.05). After the patients were grouped based on the postoperative LL apex, the postoperative LL and SS in the L5 or other lumbar spine group were significantly smaller than those in the L3 or L4 group(P<0.001), while no significant difference in postoperative GK, SVA, TK and PT was observed between the two groups. The osteotomy methods and levels were not correlated with the relocation of LL apex. In 30 patients achieving satisfying remodeling of lumbar lordosis curvature, all the spinopelvic parameters except TK were significantly improved postoperatively in both single and two-level PSO groups, and ODI and VAS scores were also significantly improved(P<0.05). Besides, no significant loss of correction was observed during follow-up. In two-level PSO group, the preoperative GK, SVA and LL were significantly larger than those in single-level PSO(P<0.05), but other preoperative parameters were similar to those in single-level PSO. ROC curves showed that the cut-off values of GK, SVA and LL were 94.50°, 19.35cm and 12.00°, respectively. The complications in the single-level PSO group included 2 cases of vertebral subluxation, 1 case of postural brachial palsy, and 1 case of intraoperative dural tear, while those in two-level PSO group included 2 cases of postural brachial palsy, 1 case of vertebral subluxation and 1 case of rod breakage during follow-up. Conclusions: Both single-level and two-level PSO could achieve satisfying remodeling of lumbar lordosis curvature for AS patients with severe thoracolumbar kyphosis, and the surgical selection is depended on the severity of preoperative kyphotic deformity. For those with GK<94.50°, SVA<19.35cm, LL<12.00°, single-level PSO should be firstly considered to achieve satisfying remodeling of lumbar lordosis. Conversely, for AS patients with more severe spinopelvic sagittal malalignment(GK≥94.50°, SVA≥19.35cm, LL≥12.00°), two-level PSO should be more recommended.