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

International Spine Study Group.

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Abstract

STUDY DESIGN.: Prospective multicenter analysis of Adult Spinal Deformity (ASD) patients. OBJECTIVE.: 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 HRQOL, but it may not be measureable on all intraoperative x-rays. In patients with prior interbody fusion at L5-S1, the plane of the S1 endplate can be blurred, creating error in PI-LL measure. The Lumbar Pelvic Angle (LPA) is more readily measured on intraoperative imaging than the TPA. METHODS.: ASD patients were included with either coronal Cobb angle >20°, SVA>5?cm, thoracic kyphosis>60°, or PT >25°. Measures of disability included ODI, SRS and SF36. Baseline and 2-yr follow-up radiographic and HRQOL outcomes were evaluated. Linear regressions compared LPA with radiographic parameters and HRQOL. RESULTS.: 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), SF36 PCS (-0.43/-0.28/-.45) SRS (-0.354/-0.23/-.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°. CONCLUSIONS.: 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 less than 7.2°. LPA predicts global alignment as it correlates with baseline and 2 year TPA and SVA. Along with the CTPA and TPA, LPA completes the fan of spinopelvic alignment.Level of Evidence: 3

Original languageEnglish (US)
JournalSpine
DOIs
StateAccepted/In press - Jul 24 2017

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ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology

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