Global Sagittal Imbalance Due to Change in Pelvic Incidence After Traumatic Spinopelvic Dissociation.

OBJECTIVES: To examine how spinopelvic morphology changes after traumatic spinopelvic dissociation and whether these changes affect the sagittal balance of the spine.

DESIGN: Retrospective analysis.

SETTING: Level I trauma center.

PATIENTS: Thirty-nine consecutive patients who were diagnosed with traumatic spinopelvic dissociation and had a minimum 2-year radiological follow-up were included.

INTERVENTION: Nineteen patients underwent spinopelvic pedicle screw fixation, 11 patients underwent percutaneous iliosacral screw fixation, and 9 patients were treated conservatively.

MAIN OUTCOME MEASUREMENTS: The main outcome measurements are as follows: (1) injury morphology (injury type and kyphotic angulation) at the initial and follow-up visits; (2) sagittal vertical axis (SVA) at the 2-year follow-up; (3) spinopelvic parameters [pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis, and thoracic kyphosis] at the 2-year follow-up; and (4) bodily pain and Oswestry Disability Index at the 2-year follow-up.

RESULTS: There were 21 men and 18 women, with a mean age of 28.3 years (15-62 years). At the 2-year follow-up, the mean SVA was 5.4 ± 4.1 cm and the mean PI was 76.9 ± 24.6 degrees. Factors related to SVA after traumatic spinopelvic dissociation were PI (r = 0.441, P = 0.017), pelvic tilt (r = 0.387, P = 0.038), and injury type of complete displacement (r = 0.372, P = 0.047). The bodily pain and Oswestry Disability Index was significantly poorer in patients with SVA modifier "+" than in patients with SVA modifier "0."

CONCLUSIONS: Lumbosacral kyphosis after traumatic spinopelvic dissociation increases PI, which can affect the sagittal balance of the spine and clinical outcome. Restoration of lumbosacral orientation is important for preventing sagittal imbalance.

LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.