Global Sagittal Balance of Spine in Asymptomatic Controls: A Systematic Review and Meta-Analysis

OBJECTIVE: To assess the global sagittal balance of spine (GSBS) in asymptomatic controls. METHODS: PubMed, Scopus, Cochrane library, and Web of Science searched up to July 2020. Studies were screened for the GSB parameters including T1 pelvic angle (TPA), spinosacral angle (SSA), sagittal vertical axis (SVA), C7/ sacrofemoral distance ratio (Barrey index), odontoid hip axis (OD-HA), and Full Balance Index (FBI) as measured in asymptomatic participants. A meta-analysis was performed to synthesize pooled estimates. Heterogeneity and publication bias were assessed. RESULTS: Overall, 76 studies were identified including 12,169 participants (54.7% female) with mean age ranges from 12.0 to 72.9 years old. We used the Newcastle-Ottawa Scale (NOS) to evaluate the quality of studies included in this review. Begg's test did not indicate obvious publication bias. The pooled analysis reveals that the mean (standard deviation) normative values were: 1) age (>)18 years, SSA (degrees), 127.6 (0.89); SVA absolute value (millimeters), 13.1 (1.13); TPA (degrees), 9.8 (1.13); T1SPI (degrees), -4.3 (0.57); and Barrey index absolute value, 0.51 (0.3). The mean value of the OD-HA (degrees) was reported 2.9 (1.6), and the FBI average value was less than 5 degrees. 2) Age <= 18 years, SSA (degrees), 132.1 (8.3); SVA absolute value (millimeters), 11.9 (2.0); and Barrey index, -0.7 (8.3). A significant difference was observed between the 2 age groups based on SVA and SSA. CONCLUSIONS: This paper presents normative data on TPA, SSA, SVA, Barrey index, OD-HA, and FBI as a reference for evaluating/measuring a GSB of spine in asymptomatic controls.