Age-based normal sagittal alignment in Chinese asymptomatic adults: establishment of the relationships between pelvic incidence and other parameters.

PURPOSE

To investigate the age-based normal values of sagittal parameters and establish the relationships between them in Chinese population.

METHOD

Two hundred eighteen asymptomatic adult volunteers were included in this cross-sectional study. The whole spine standing radiograph was taken from them, and the parameters including sagittal vertical axis (SVA), T1 pelvic angle (TPA), global tilt (GT), spino-sacral angle, lumbar lordosis (LL), thoracic kyphosis (TK), T1 slope (T1S), cervical lordosis (CL), C2-C7SVA, pelvic tilt (PT), sacral slop (SS) and pelvic incidence (PI) were measured. The gender differences in sagittal alignment were compared. Pearson correlation was calculated, and a linear regression analysis was used to establish the relation between PI and other parameters.

RESULTS

The average values of PI, LL, TPA and GT were 46.2°, 48.2°, 7.8° and 10.6°, respectively, in this cohort. SVA, GT, TPA, TK, T1S, CL and PT significantly increased with age (p < 0.05). The females presented smaller T1S, C2-C7SVA and larger PI, PT than the males. The relationships between PI and TPA, GT, SS, LL could be presented as TPA = 0.411 * PI - 11.2 (R = 0.328, p < 0.001), GT = 0.483 * PI - 11.7 (R = 0.297, p < 0.001), SS = 0.354 * PI + 16.1 (R = 0.203, p < 0.001), LL = 0.588 * PI + 21.0 (R = 0.267, p < 0.001), respectively.

CONCLUSION

The normal values of sagittal parameters were presented and changed with age in Chinese asymptomatic population. The gender differences existed in sagittal parameters. The relationships between PI and other parameters were established which could be used for further research. These slides can be retrieved under Electronic Supplementary Material.