Influence of the Ratio of C2–C7 Cobb Angle to T1 Slope on Cervical Alignment After Laminoplasty

• Published in: World neurosurgery Vol. 124; pp. e659 - e666
• Main Authors: Li, Xiang-Yu, Kong, Chao, Sun, Xiang-Yao, Guo, Ma-Chao, Ding, Jun-Zhe, Yang, Yi-Ming, Lu, Shi-Bao
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2019
• Subjects: Cervical spondylotic myelopathy; Kyphotic alignment change; Laminoplasty; Sagittal alignment; Sagittal balance; Sagittal alignment; Kyphotic alignment change; cSVA; LR; Laminoplasty; CL/T1S; HR; CSM; FR; JOA; Cervical spondylotic myelopathy; Sagittal balance
• ISSN: 1878-8750; 1878-8769
• DOI: 10.1016/j.wneu.2018.12.181

To assess the relationship between the ratio of C2–C7 Cobb angle to T1 slope (CL/T1S) and cervical alignment changes after laminoplasty. 78 consecutive patients with cervical myelopathy who underwent laminoplasty were enrolled. All patients with preoperative and follow-up cervical spine lateral x-ray images available for review were recruited in this study. Imaging data included C2–C7 Cobb angle, T1 slope, and cervical sagittal vertical axis (cSVA). All patients were classified into low-ratio group (bottom 25% of CL/T1S), fair-ratio group (middle 50% of CL/T1S), and high ratio group (top 25% of CL/T1S) according to CL/T1S ratio. The recovery rate was calculated based on the Japanese Orthopedic Association score. The preoperative C2–C7 Cobb angle had significant correlations with the T1 slope (r = 0.528). Kyphotic alignment changes in the group with a high ratio of CL/T1S was greater than that of the other 2 groups (P < 0.001). The incidence of postoperative kyphosis in the group with a low ratio of CL/T1S was higher than that of the other 2 groups (P < 0.001). There was no postoperative kyphosis in the fair-ratio group. The surgical outcome in the low-ratio CL/T1S group and the high-ratio CL/T1S group was poorer than that in the fair-ratio CL/T1S group (P = 0.005). The cervical alignment was kept well in the mid-range CL/T1S ratio group after laminoplasty. Patients with a high CL/T1S ratio were more likely to present with kyphotic alignment changes. Patients with a low CL/T1S ratio were more likely to have postoperative kyphosis.