The Role of Spinopelvic Parameters in Clinical Outcomes of Spinal Osteotomies in Patients with Sagittal Imbalance

Background: Sagittal imbalance is known as the main radiographic driver of disability in adult spinal deformity (ASD). In this study, the association of radiological spinopelvic parameters and clinical outcomes was evaluated following the corrective surgery of sagittal imbalance, in order to explore the predictive ability of each parameter. Methods: A total of 23 patients, who underwent corrective osteotomy for restoration of sagittal balance, were included in this study. The mean follow-up period of the patients was 15.5±2.1, ranging from 12 to 18 months. Pre- and postoperative radiological parameters including pelvic tilt (PT), sagittal vertical axis (SVA) and pelvic incidence minus lumbar lordosis (PI-LL) were assessed for each patient. Clinical outcomes were evaluated using Oswestry disability Index (ODI). Results: The mean ODI improved 32% following the corrective osteotomy of sagittal imbalance. Postoperative ODI was significantly correlated with all preoperative radiological parameters (r=0.608, P=0.002 for PI-LL; r=0.483, P=0.01 for PT; and r=0.464, P=0.02 for SVA). ODI improvement was significantly correlated with PI-LL and SVA change (r=536, P=0.008 and r=416, P=0.04, respectively), but not with PT change (r=247, P=0.25). The outcome was better in pedicle subtraction osteotomy (PSO) compared to Smith-Petersen Osteotomy (SPO).Conclusion: Surgical correction of sagittal imbalance could limit the amount of disability caused by this misalignment. According to our results, while all the spinopelvic parameters could be used in the prediction of the outcomes of corrective surgery of sagittal imbalance, PI-LL was the most informative parameter and more attention should be devoted to this parameter. Level of evidence: IV