Objective To analyse the correlation between cervical sagittal parameters of cervical spondylotic myelopathy in different sagittal curvature so as to find out representative cervical sagittal alignment parameters by measuring on MRI. Methods A retrospective analysis was made on the clinical data of 88 patients with cervical spondylotic myelopathy between July 2015 and January 2016. The C2-C7 Cobb angle, T1 slope (T1S), and C2-C7 sagittal vertical axis (C2-C7 SVA) were measured on T2-weight MRI. According to C2-C7 Cobb angle, the patients were divided into lordosis group (≥10° Cobb angle, 48 cases) and straightened group (0-10° Cobb angle, 40 cases). Intraclass correlation coefficient (ICC) was used for the reliability of measured data, Pearson correlation analysis for correlation between cervical sagittal parameters. Results ICC was 0.858-0.946, indicating good consistency of measurement parameters. The C2-C7 Cobb angle, T1S, and C2-C7 SVA were (5.6±2.4)°, (22.2±6.7)°, and (10.2±5.4) mm in straightened group, and were (20.1±8.2)°, (23.4±8.9)°, and (8.2±4.6) mm in lordosis group respectively. There was no correlation between the 3 parameters in straighten group (r=0.100,P=0.510 for T1S and C2-C7 Cobb angle;r=–0.100,P=0.500 for T1S and C2-C7 SVA;r=0.080,P=0.610 for C2-C7 Cobb angle and C2-C7 SVA). There was positive correlation between T1S and C2-C7 Cobb angle (r=0.540,P=0.000), negative correlation between T1S and C2-C7 SVA (r=–0.450,P=0.001), and no correlation between C2-C7 Cobb angle and C2-C7 SVA (r=–0.003,P=0.980). Conclusion For cervical spondylotic myelopathy in patients with cervical lordosis, only T1S measurement on MRI can be used as the main parameter to judge the sagittal curvature, but in patients with straightened cervical Cobb angle, measurements of T1S, C2-C7 Cobb angle, and C2-C7 SVA should be taken for the comprehensive evaluation of cervical sagittal curvature.
ZHANG Lilong, CHENG Zhaojun, CUI Zijian, REN Zhishuai, PENG Bing, ZHANG Xueli. Analysis of cervical sagittal parameters on MRI in patients with cervical spondylotic myelopathy. Chinese Journal of Reparative and Reconstructive Surgery, 2017, 31(4): 451-454. doi: 10.7507/1002-1892.201610119