颈椎单开门椎管扩大成形侧块螺钉内固定术术后颈椎矢状位参数变化及平衡代偿机制分析

Changes of sagittal parameters and balance compensation mechanism of cervical spine after modified open-door laminoplasty

目的探讨颈椎单开门椎管扩大成形加C4~6侧块螺钉内固定术术后颈椎和上胸椎相关参数变化情况,并初步分析术后颈椎矢状位平衡代偿的规律。方法采用回顾性研究方法,选取2017年8月至2018年7月因脊髓型颈椎病于首都医科大学附属北京友谊医院行颈椎后路单开门椎管扩大成形加C4~6侧块螺钉内固定术治疗的24例患者。通过侧位X线分别测量患者术前、术后即刻、术后6个月C2~7Cobb's角、C2~7SVA值、颈椎倾斜度、头颅倾斜度、T1倾斜角、胸廓入射角(TIA)等颈椎矢状位参数。运用重复测量方差分析和Pearson相关性分析进行统计学分析。结果24例患者术前、术后即刻、术后6个月T1倾斜角[(19.90±4.50)°vs.(19.61±5.40)°vs.(19.90±6.33)°)]、TIA[(75.38±5.48)°vs.(75.42±6.11)°vs.(74.46±7.23)°)]、C2~7Cobb's角[(16.40±6.71)°vs.(15.36±7.55)°vs.(15.70±8.03)°)],上述参数术前、术后差异无统计学意义。但C2~7SVA[(1.88±0.82)cmvs.(2.25±1.16)cmvs.(2.39±1.23)cm]、头颅倾斜角[(7.71±4.08)°vs.(9.88±5.20)°vs.(10.32±6.15)°)]、颈椎倾斜度[(8.19±2.96)°vs.(7.26±2.60)°vs.(7.10±2.34)°)]差异具有统计学意义。不论术前还是术后,T1倾斜角与C2~7SVA及C2~7Cobb's角均显著相关,但C2~7Cobb's角与SVA无显著性相关。术后3例患者出现颈椎矢状位失衡,6例患者可以通过减少T1倾斜度代偿维持颈椎矢状位平衡。结论单开门椎管扩大成形加C4~6侧块螺钉内固定术术后颈椎前凸保持良好,但C2~7SVA较术前显著增加。大部分患者术后颈椎矢状位平衡良好,部分患者还可以通过术后减小T1倾斜角来进行代偿,极少数患者术后会出现颈椎矢状位失衡。

Objective To evaluate the changes of cervical and upper thoracic spinal parameters and analyze the compensatory of cervical sagittal balance after laminoplasty with C 4-6 lateral mass screws fixation and fusion. Methods 24 patients were enrolled retrospectively. They were diagnosed as cervical spondylotic myelopathy and had undergone laminoplasty with C 4-6 lateral mass screws fixation and fusion in Beijing Friendship Hospital,Capital Medical University between August 2017 and July 2018. All patients underwent routine cervical spine lateral X-ray pre- and post operation and at 6th month fellow-up. C 2-7 angle,C 2-7 SVA,cranial tilt,cervical tilt,TIA,T1 slope were recorded. Repeated measures ANOVA and Pearson correlation coefficients were performed for statistical analysis. Results The mean pre-,post-operation and 6th month fellow-up of T1 slope was (19.90±4.50)°,(19.61±5.40)°and (19.90±6.33)°,respectively. There was no significant difference between them. There was no significant difference in TIA [(75.38±5.48)° vs.(75.42±6.11)° vs.(74.46±7.23)°] or C 2-7 angle [(16.40±6.71)° vs.(15.36±7.55)° vs (15.70±8.03)°]. But there were significant differences in C 2-7 SVA [(1.88±0.82) cm vs.(2.25±1.16) cm vs.(2.39±1.23) cm],cranial tilt [(7.71±4.08)° vs.(9.88±5.20)° vs.(10.32±6.15)°]and cervical tilt [(8.19±2.96)° vs.(7.26±2.60)° vs.(7.10±2.34)°]. There was a significant relationship between T1 slope and C 2-7 SVA,T1 slope and C 2-7 angle,whatever pre- and post-operation. But there was no correlation between C 2-7 angle and SVA. There were 3 cases who appeared cervical sagittal imbalance after operation. The decrease of T1 slope after operation was observed in 6 patients. Conclusion After treatment with laminoplasty and C 4-6 lateral mass screw fixation and fusion,the patients' cervical lordosis can be maintained well but C 2-7 SVA increased significantly. Some patients can decrease T1 slope to preserve the cervical sagittal balance and very few patients may appear cervical sagittal imbalance after operation.