Normative Thoracic, Lumbar, Pelvic and Global Sagittal Alignment Parameters for Asymptomatic Adults

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. 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 to T12 TK), regional TK (T4-5 to T12), lumbar lordosis to L5 (T12-L1 to L5, LL-L5), LL to S1 (T12-L1 to 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. >60 yrs), ethnic group (Asian, Caucasian, Hispanic, Middle Eastern), and Asian subgroup (Chinese, Japanese, 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: 18-93 years were included. Regional TK and PT increased significantly in patients >60 compared to 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, 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 Asian subgroup. Global alignment was largely equivalent across ethnic groups.