The spino-pelvic ratio: a novel global sagittal parameter associated with clinical outcomes in adult spinal deformity patients.

Journal Article (Journal Article)

PURPOSE: Analysis of interactions of spinal alignment metrics may uncover novel alignment parameters, similar to PI-LL. This study utilized a data-driven approach to hypothesis generation by testing all possible division interactions between spinal alignment parameters. METHODS: This study was a retrospective cohort analysis. In total, 1439 patients with baseline ODI were included for hypothesis generation. In total, 666 patients had 2-year postoperative follow-up and were included for validation. All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI. RESULTS: From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Conceptually, the TPA divided by PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral endplate. The mean TPA/PI was 0.41 at baseline and 0.30 at 2 years postoperatively. Higher TPA/PI was associated with worse baseline ODI (p < 0.0001). The change in ODI at 2 years was linearly associated with the change in TPA/PI (p = 0.0172). The optimal statistical grouping of TPA/PI was low/normal (≤ 0.2), medium (0.2-0.4), and high (> 0.4). The R-squared for ODI against categorical TPA/PI alone (0.154) was directionally higher than that for each of the individual Schwab modifiers (SVA: 0.138, PI-LL 0.111, PT 0.057). CONCLUSION: This study utilized a data-driven approach for hypothesis generation and identified the spino-pelvic ratio (TPA divided by PI) as a promising measure of sagittal spinal alignment among ASD patients. Patients with SPR > 0.2 exhibited inferior ODI scores. LEVEL OF EVIDENCE: III.

Full Text

Duke Authors

Cited Authors

  • Durand, WM; Daniels, AH; Hamilton, DK; Passias, P; Kim, HJ; Protopsaltis, T; LaFage, V; Smith, JS; Shaffrey, C; Gupta, M; Kelly, MP; Klineberg, E; Schwab, F; Burton, D; Bess, S; Ames, C; Hart, R; International Spine Study Group (ISSG),

Published Date

  • September 2020

Published In

Volume / Issue

  • 29 / 9

Start / End Page

  • 2354 - 2361

PubMed ID

  • 32488440

Electronic International Standard Serial Number (EISSN)

  • 1432-0932

Digital Object Identifier (DOI)

  • 10.1007/s00586-020-06472-x


  • eng

Conference Location

  • Germany