Analysis of the cervical spine alignment and its correlation with spino-pelvic balance in asymptomatic young adults

English Keywords:Cervical sagittal alignment  SVA  Cervical types

English Abstract:

  【Abstract】 Objectives: To describe the normal range of cervical sagittal parameters in Asian Yellow People, to analyze the factors determining cervical spine sagittal balance and compare the parameters among four types of cervical spine. Methods: A prospective radiographic study on 132 asymptomatic young volunteers without the history of symptoms related to whole spine was carried out. Cervical and whole-spine standing lateral radiographs were taken to analyze the following parameters: spino-pelvic parameters including pelvic incidence(PI）, sacral slope(SS), lumbar lordosis(LL), and sagittal thoracic parameters including thoracic kyphosis(TK), T1 slope; and cervical spine parameters including C0-C2, C2-C7 angles and C2-C7 SVA, CGH-C7 SVA, CGH-C2 SVA, and global spine parameters. Statistical analysis was performed by using the spinal sacral angle(SSA), C7-S1 SVA. Three groups were assigned according to Toyama method: lordosis group, kyphosis group, straight or sigmoid group. Pearson correlation coefficients and one-way-ANOVA(Student-Newman-Keuls test) were used. Results: All the parameters showed a normal distribution. The mean C0-C2 angle was 15.13°±6.69°, and the mean C2-C7 angle was 12.03°±7.64°. The mean C2-C7 SVA was 18.67±7.96mm, and the mean CGH-C7 SVA was 22.95±12.18mm, and the mean CGH-C2 SVA was 7.08±5.38mm. The mean T1 slope was 26.33°±7.01°. In 3 groups, lordosis group had 43(32.6%), straight or sigmoid group had 74(56.1%), kyphosis group had 15(11.3%). There was a significant sequential linkage between C0-C2 angle and C2-C7 angle(r=-0.277), C2-C7 angle and T1 slope(r=0.422), T1 slope and TK(r=0.434), TK and LL(r=0.574), LL and SS(r=0.459), SS and PI(r=0.727). C2-C7 angle, CGH-C7 SVA, T1 slope, TK showed significant differences among the three groups of cervical alignment. Conclusions: Cervical lordosis is not the only presentation in asymptomatic subjects. The cervical alignment correlates with the gravity of head and thoracic kyphosis, and cervical kyphosis may be a local problem rather than the global spine and pelvis parameter anomaly.