Normative Thoracic, Lumbar, Pelvic, and Global Sagittal Alignment Parameters for Asymptomatic Adults: A Systematic Review and Meta-Analysis of >35,900 Volunteers.

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

To describe regional and global spinopelvic sagittal parameters in asymptomatic adults.

SUMMARY OF BACKGROUND DATA

Understanding normal alignment is important for management of patients with spinal deformities and essential for patient well-being following corrective surgery. To our knowledge, there exists no meta-analyses on normative alignment.

MATERIALS AND METHODS

We searched PubMed for primary studies on asymptomatic individuals with normal spinal anatomy and no prior spinal intervention. The collected variables included: age, gender percentage, global thoracic kyphosis (T1-3-T12 TK), regional TK (T4-5-T12), lumbar lordosis to L5 (T12-L1-L5, LL-L5), LL to S1 (T12-L1-S1, LL-S1), sacral slope (SS), pelvic incidence (PI), pelvic tilt (PT), PI-LL mismatch, sagittal vertical axis (SVA), T1 pelvic angle (TPA), and spinosacral angle (SSA). Data was analyzed according to sex, age (20-40 vs. 40-60 vs. greater than 60 yrs), ethnic group (Asian, Caucasian, Hispanic, and Middle Eastern), and Asian subgroup (Chinese, Japanese, and Korean).

RESULTS

A total of 191 articles from 27 countries including 35,913 participants were reviewed: 16,125 men (44.9%), 18,222 women (50.7%), age range: 18 to 93 years were included. Regional TK and PT increased significantly in patients >60 compared with other groups. Globally, SVA, TPA, and changed with age in patients >60.

CONCLUSION

LL-S1, PI and PT were all higher in women. Regional TK, PT, PI-LL, SVA, and TPA all increased with age, while LL-S1 and SSA decreased. Global TK, regional TK, LL-S1, PI, and PI-LL all had significant differences across broad ethnic groups, and LL-S1, PI, PT, and SVA showed differences within the Asian subgroup. Global alignment was largely equivalent across ethnic groups.