顶椎区置钉/钩对1型神经纤维瘤病萎缩性脊柱侧凸患者脱位肋骨头椎管内迁移的影响

The influence of screw/hook insertion at apical vertebrae with rib head dislocation on degree of extraction of penetrated rib head from spinal canal in dystrophic scoliosis secondary to type 1 neurofibromatosis

目的:探讨顶椎区脱位肋骨头相应胸椎置钉/钩对1型神经纤维瘤病萎缩性脊柱侧凸(dystrophic scoliosis secondary to type 1 neurofibromatosis,NF1-DS)患者脱位肋骨头椎管内迁移的影响。方法:2007年12月~2014年4月共收治18例伴肋骨头脱位的NF1-DS患者,男女各9例,年龄8~23岁(13.3±3.7岁)。其中7例接受单纯后路矫形手术,4例后路矫形术前行Halo轮椅牵引,3例一期同时行前路骨骺阻滞术及后路矫形手术,2例在后路矫形术后二期行前路补充性融合,1例行一期前路松解+骨骺阻滞及二期后路矫形手术,1例在多次生长棒治疗后行后路矫形。脱位侵入椎管的肋骨共计24处,分布在顶椎(apex)11处(45.8%),apex+1(尾端)8处(33.3%),apex-1(头端)5处(20.9%),均未行肋骨头切除或旷置手术。根据顶椎区脱位肋骨头相应胸椎置钉/钩与否分组,独立样本t检验分析比较两组间脱位肋骨头侵入椎管长度(intraspinal rib length,IRL)的矫正率是否存在差异。采用多元线性回归法评估Cobb角矫正、脱位肋骨头相应椎体平移(vertebral translation,VT)和去旋转(vertebral rotation,VR)的矫正对脱位肋骨头椎管内迁移即IRL矫正的影响。结果:8例患者行全椎弓根螺钉系统内固定,10例为钉钩混合系统内固定,平均固定节段数为11.7,置入物密度63%。主胸弯Cobb角和全脊柱最大后凸角(global kyphosis,GK)分别由术前的66.6°±15.4°、56.4°±17.3°矫正至术后即刻的36.1°±16.7°、35.1°±16.6°(P<0.001)。与术前比较,术后即刻IRL显著减小(9.4±3.8mm vs.5.1±3.8mm,P<0.001)。顶椎区脱位肋骨头相应胸椎置钉/钩组共17处,其IRL矫正率和Cobb角矫正率显著大于未置钉/钩组(7处)[(56.1±23.9)%vs.(32.6±8.0)%,P<0.05;(48.9±15.7)%vs.(33.5±16.3)%,P<0.05],两组VT和VR矫正率均无统计学差异[(31.6±27.6)%vs.(22.6±11.7)%,P>0.05;(13.8±23.4)%vs.(7.4±12.3)%,P>0.05]。多元线性回归分析显示Cobb角矫正率对IRL矫正率有显著影响(β=0.602,P=0.029)。结论:顶椎区伴肋骨头脱位的NF1-DS患者胸椎置钉/钩及增大Cobb角矫正率可增加脱位肋骨头自发性迁移退出椎管的复位程度。

Objectives： To investigate the influence of screw/hook insertion at apical vertebrae with rib head dislocation on the degree of extraction of penetrated rib head from spinal canal in dystrophic scoliosis secondary to type 1 neurofibromatosis（NF1-DS）. Methods： 18 NF1-DS patients with intraspinal rib head dislocation treated surgically from December 2007 to April 2014 were retrospectively reviewed. There were 9 males and 9 females, and the average age was 13.3±3.7 years. The surgical strategies were posterior spinal fusion on 7 patients, posterior spinal fusion（PSF） with preoperative halo traction on 4 patients, one-stage PSF with convex growth arrest（CGA） on 3 patients, staged supplemental anterior fusion following PSF on 2 patients, staged anterior release, CGA and PSF on 1 patient and staged growing rod technique with final PSF on 1 patient. The location of dislocated rib heads being categorized as apex accounted for the largest share in total （11, 45.8%）, followed by apex＋1（8, 33.3%） and apex-1（5, 20.9%）, and no rib head excision was performed. The patients were stratified by the presence of screw/rod insertion at vertebrae with rib head dislocation. Comparisons were made to investigate whether the degree of extraction of penetrated rib head from spinal canal differed between two groups by using independent sample t test. It was explored whether correction of Cobb angle, vertebral rotation and translation（VT, VS） could contribute to the extraction of intra-canal rib head by linear regression analysis. Results： The spinal implant constructs were all pedicle screws on 8 patients and hybrid hook-screw constructs on 10 patients, the average number of fusion segments was 11.7, and the implant density averaged 63%. The thoracic Cobb angle and global kyphosis（GK） improved from 66.6°±15.4° and 56.4°±17.3° to 36.1°±16.7° and 35.1°±16.6°, respectively（P〈0.001）. Paired sample t-tests revealed significant reduction in intraspinal rib length（IRL） postoperatively（9.4±3.8mm vs. 5.1±3.8mm, P〈0.001）. The correction rates of IRL and Cobb angle were significantly larger for the 17 penetrated ribs with screw/rod insertion[（56.1±23.9）% vs. （32.6±8.0）%, P〈0.05; （48.9±15.7）% vs. （33.5±16.3）%, P〈0.05]. Moreover, the correction rates of VT and VR were also larger but didn not reach statistical significance[（31.6±27.6）% vs. （22.6±11.7）%, P〉0.05; （13.8±23.4）% vs. （7.4±12.3）%, P〉0.05]. Multiple linear regression analysis demonstrated that the correction rate of Cobb angle contributed significantly to correction of IRL（β=0.602, P=0.029）. Conclusions： Screw/hook insertion at apical vertebrae with penetrated rib head contributes significantly to the degree of extraction of penetrated rib head from spinal canal. This effect can be strengthened by more correction of Cobb angle.