Normative values of cervical sagittal alignment according to global spine balance: based on 126 asymptomatic Chinese young adults.

Abstract

To explore the normal distribution of cervical sagittal alignment and the relationship between cervical alignment and global spine balance in asymptomatic young adults. 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. 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). 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. Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.