Xipho-pubic angle (XPA) correlates with patient's reported outcomes in a population of adult spinal deformity: results from a multi-center cohort study.

STUDY DESIGN: Retrospective multi-center cohort study.

PURPOSE: Sagittal misalignment causes changes in the abdominal shape. Xipho-pubic angle (XPA) has been previously described to radiographically evaluate the shape of the abdominal cavity in patients with spine deformity. The aims of this study are to evaluate the correlation of XPA-to-spinopelvic sagittal parameters and to patients' health-related quality-of-life (HRQoL) scores.

METHODS: 278 patients from a multi-center database with diagnosis adult spinal deformity (ASD) (one or more of: coronal Cobb angle > 20°, sagittal vertical axis (SVA) > 50 mm, pelvic tilt (PT) > 25°, and thoracic kyphosis > 60°) were included. Cut-off values for moderate and severe disability (ODI-Oswestry Disability Index-20 and 40%) were calculated. Pearson's correlation was tested between XPA and spinopelvic parameters and between XPA and HRQoL scores.

RESULTS: The cut-off value of XPA to identify ODI severe disability (40/100) was identified with XPA smaller than 103°; minimal (20/100) disability was identified by XPA greater than 113°. XPA showed strong correlation to sagittal spinopelvic parameters-PT, SVA, lumbar lordosis (LL), pelvic incidence (PI) minus LL-and to HRQoL scores-ODI, SF-36 PCS and SRS-22 activity and pain. XPA was the parameter with the strongest correlation to HRQoL scores.

CONCLUSIONS: Xipho-pubic angle reflects changes in spinal changes and has strong correlation to HRQoL and spinopelvic parameters. It can discriminate between patients with minimal, moderate, and severe disability as measured by ODI scores. These slides can be retrieved under Electronic Supplementary Material.