The Lumbar Pelvic Angle, the Lumbar Component of the T1 Pelvic Angle, Correlates with HRQOL, PI-LL Mismatch, and it Predicts Global Alignment

Themistocles S. Protopsaltis, Renaud Lafage, Justin S. Smith, Peter G. Passias, Christopher I. Shaffrey, Han Jo Kim, Gregory M. Mundis, Christopher P. Ames, Douglas C. Burton, Shay Bess, Eric Klineberg, Robert A. Hart, Frank J. Schwab, Virginie Lafage

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38 Scopus citations


Study Design. Prospective multicenter analysis of adult spinal deformity (ASD) patients. Objective. The aim of this study was to introduce the lumbar pelvic angle (LPA), a novel parameter of spinopelvic alignment. Summary of Background Data. The T1 pelvic angle (TPA), a measure of global spinopelvic alignment, correlates with health-related quality of life (HRQOL), but it may not be measureable on all intraoperative x-rays. In patients with previous interbody fusion at L5-S1, the plane of the S1 endplate can be blurred, creating error in pelvic incidence and lumbar lordosis (PI-LL) measure. The LPA is more readily measured on intraoperative imaging than the TPA. Methods. ASD patients were included with either coronal Cobb angle >20°, sagittal vertical axis (SVA) >5 cm, thoracic kyphosis >60°, or pelvic tilt (PT) >25°. Measures of disability included Oswestry Disability Index (ODI), Scoliosis Research Society (SRS), and Short Form (SF)-36. Baseline and 2-year follow-up radiographic and HRQOL outcomes were evaluated. Linear regressions compared LPA with radiographic parameters and HRQOL. Results. A total of 852 ASD patients (407 operative) were enrolled (mean age 53.7). Baseline LPA correlated with PI-LL (r = 0.79), PT (r = 0.78), TPA (r = 0.82), and SVA (r = 0.61) (all P < 0.001). PI-LL, LPA, and TPA correlated with ODI (r = 0.42/0.29/0.45), SF-36 physical component score (-0.43/-0.28/-0.45) SRS (-0.354/-0.23/-0.37) with all P < 0.001. At 2 years' follow-up, LPA correlated with PI-LL (r = 0.77), PT (r = 0.78), TPA (r = 0.83), and SVA (r = 0.57) (all P < 0.001). Categorizing patients by increasing LPA (<7°; 7°-15°; >15°) revealed progressive increases in all HRQOL, PI-LL (-3.2°/12.7°/32.4°), and TPA (9.7°/20.1°/34.6°) with all P < 0.001. Moderate disability (ODI = 40) corresponded to LPA 10.1°, PI-LL 12.6°, and TPA 20.6°. Mild disability (ODI = 20) corresponded to LPA 7.2°, PI-LL 4.2°, and TPA 14.7°. Conclusion. LPA correlates with TPA, PI-LL, and HRQOL in ASD patients. LPA can be used as an intraoperative tool to gauge correction with a target LPA of <7.2°. LPA predicts global alignment, as it correlates with baseline and 2-year TPA and SVA. Along with the cervical-thoracic pelvic angle and TPA, LPA completes the fan of spinopelvic alignment. Level of Evidence: 3.

Original languageEnglish (US)
Pages (from-to)681-687
Number of pages7
Issue number10
StatePublished - May 15 2018


  • T1-pelvic angle
  • adult spinal deformity surgery
  • global spinopelvic alignment
  • health-related quality of life
  • interbody fusion
  • intraoperative planning
  • lumbar pelvic angle
  • patient-reported outcomes
  • radiographic parameters
  • sagittal malalignment
  • thoracolumbar surgery

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology


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