Purpose: To explore the normal distribution of cervical sagittal alignment and the relationship between cervical alignment and global spine balance in asymptomatic young adults.
Methods: A total of 67 males and 59 females aged from 18 to 30 years old were recruited from 11/2011 to 12/2014. The C0-C2 angle, disk angles from C2-C3 to C6-C7, vertebral angles from C3 to C7, T1 slope, thoracic kyphosis (TK), lumbar lordosis, pelvic incidence, sacral slope, C2-C7 sagittal vertical axis (SVA), center of gravity of head to C7 SVA (CGH-C7SVA), C7-S1SVA were measured and statistically analyzed. The Roussouly classification was utilized.
Results: Mean value of C0-C7 was 26.0° ± 12.8°, composed of 15.2° ± 6.7° for C0-C2, 9.1° ± 12.1° for sum of disk angles from C2-C3 to C6-C7, and 1.4° ± 10.2° for sum of vertebral angles from C3 to C7. C2-C7SVA (18.6 mm ± 7.9 mm) and CGH-C7SVA (22.9 mm ± 12.3 mm) were offset ideally by C7-S1SVA (-21.6 mm ± 31.0 mm). Significant difference was found between cervical alignment of different Roussouly types (p < 0.01). There was significant correlation between cervical alignment and T1 slope (p < 0.01), TK (p < 0.01). There was significant correlation between adjacent segmental angles from T1 slope up to C0-C2 angle (p < 0.05).
Conclusion: Normative values of each vertebral angle and disk angle were established. The cervical lordosis occurred mainly at C0-C2 and disk levels, which was influenced by parameters of other parts of the spine, such as T1 slope, TK and the Roussouly classification. There was significant correlation between adjacent disk angles.
Level of evidence i: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.
Keywords: Cervical spine; Disk angle; Global spine balance; Sagittal alignment; Vertebral angle.
© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.