Prospective multicenter analysis of adult spinal deformity (ASD) patients.
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.
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
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°.
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