RT Journal Article SR Electronic T1 Suboptimal Age-Adjusted Lumbo-Pelvic Mismatch Predicts Negative Cervical-Thoracic Compensation in Obese Patients JF International Journal of Spine Surgery JO Int J Spine Surg FD International Society for the Advancement of Spine Surgery SP 6034 DO 10.14444/6034 A1 Samantha R. Horn A1 Cole A. Bortz A1 Subaraman Ramachandran A1 Gregory W. Poorman A1 Frank Segreto A1 Matt Siow A1 Akhila Sure A1 Dennis Vasquez-Montes A1 Bassel Diebo A1 Jared Tishelman A1 John Moon A1 Peter Zhou A1 Bryan Beaubrun A1 Shaleen Vira A1 Cyrus Jalai A1 Charles Wang A1 Kartik Shenoy A1 Omar Behery A1 Thomas Errico A1 Virginie Lafage A1 Aaron Buckland A1 Peter G. Passias YR 2019 UL http://ijssurgery.com//content/early/2019/07/09/6034.abstract AB Background Given the paucity of literature regarding compensatory mechanisms used by obese patients with sagittal malalignment, it is necessary to gain a better understanding of the effects of obesity on compensation after comparing the degree of malalignment to age-adjusted ideals. This study aims to compare baseline alignment of obese and nonobese patients using age-adjusted spino-pelvic alignment parameters, describing associated spinal changes.Methods Patients ≥ 18 years with full-body stereoradiographs were propensity-score matched for sex, baseline pelvic incidence (PI), and categorized as nonobese (body mass index < 30kg/m2) or obese (body mass index ≥ 30). Age-adjusted ideals were calculated for sagittal vertical axis, spino-pelvic mismatch (PI-LL), pelvic tilt, and T1 pelvic angle using established formulas. Patients were stratified as meeting alignment ideals, being above ideal, or being below. Spinal alignment parameters included C0-C2, C2-C7, C2-T3, cervical thoracic pelvic angle, cervical sagittal vertical axis SVA, thoracic kyphosis, T1 pelvic angle, T1 slope, sagittal vertical axis, lumbar lordosis (LL), PI, PI-LL, pelvic tilt. Lower-extremity parameters included sacrofemoral angle, knee flexion (KA), ankle flexion (AA), pelvic shift (PS), and global sagittal angle (GSA). Independent t tests compared parameters between cohorts.Results Included: 800 obese, 800 nonobese patients. Both groups recruited lower-extremity compensation: sacrofemoral angle (P = .004), KA, AA, PS, GSA (all P < .001). Obese patients meeting age-adjusted PI-LL had greater lower-extremity compensation than nonobese patients: lower sacrofemoral angle (P = .002), higher KA (P = .008), PS (P = .002), and GSA (P = .02). Obese patients with PI-LL mismatch higher than age-adjusted ideal recruited greater lower-extremity compensation than nonobese patients: higher KA, AA, PS, GSA (all P < .001). Obese patients showed compensation through the cervical spine: increased C0-C2, C2-C7, C2-T3, and cervical sagittal vertical axis (all P < .001), high T1 pelvic angle (P < .001), cervical thoracic pelvic angle (P = .03), and T1 slope (P < .001), with increased thoracic kyphosis (P = .015) and decreased LL (P < .001) compared to nonobese patients with PI-LL larger than age-adjusted ideal.Conclusions Regardless of malalignment severity, obese patients recruited lower-limb compensation more than nonobese patients. Obese patients with PI-LL mismatch larger than age-adjusted ideal also develop upper-cervical and cervicothoracic compensation for malalignment.Level of Evidence IIIClinical Relevance Clinical evaluation should extend to the cervical spine in obese patients not meeting age-adjusted sagittal alignment ideals.