THE GLOBAL TILT: EVALUATION OF A PARAMETER CONSIDERING THE GLOBAL SPINOPELVIC ALIGNMENT.

Purpose: Regarding the close interaction between the spinal balance and the pelvis orientation no parameter is routinely used to describe and to evaluate the global spinopelvic balance, taking into account simultaneously the spinal part and the pelvic part of the global alignment. The global tilt was described to analyze malalignment, considering spinal and pelvic imbalance together. From a geometrical point of view, the global tilt is the sum of the C7 vertical tilt and the pelvic tilt. The aim of this study is to evaluate the global tilt by analyzing its correlation with spinal malalignment.

Methods: A cohort of patients who underwent a lumbar pedicle subtraction osteotomy (PSO) for major sagittal malalignment was realized. All patients had preoperative and postoperative full spine EOS radiographies to measure spinopelvic parameters. The lack of lordosis was calculated after prediction of theoretical lumbar lordosis. Correlation analysis between different spinopelvic parameters, including the global tilt, was performed for preoperative and postoperative values.

Results: Thirty-one consecutive patients were included. All parameters were correlated with spinal malalignment but the global tilt was the most correlated parameter in preoperative (r = 0.71) and in postoperative (r = 0.78). When spinal and pelvic parameters were analyzed separately, 19% of patients presented mismatches between spine and pelvis.

Conclusion: This study highlights the interest of a global parameter evaluating the spinal balance and the pelvic balance together. The global tilt appeared to be the most correlated parameter in this study with spinal malalignment and could be used for the interpretation of clinical series in spine surgery.