Preoperative Cervical Hyperlordosis and C2–T3 Angle are Correlated to Increased Risk of Post-Op Sagittal Spinal Pelvic Malalignment in Adult Spinal Deformity Patients at 2-Year Follow-Up

Abstract

Introduction Cervical deformity (CD) is prevalent among patients with adult spinal deformity (ASD). The effect of baseline cervical alignment and achieving optimal TL alignment in ASD surgery is unclear. This study assesses the relationship between preoperative cervical spinal parameters and global alignment following thoracolumbar ASD surgery at 2-year follow-up. Patients and Methods Using a multicenter prospective database of surgical patients with ASD, we included patients with 2-year follow-up and cervical X-rays. SRS-Schwab sagittal modifiers (PT, GA, and PI–LL) were assessed at 2-year postoperative as either normal (0) or abnormal (“ + ” or “ + +”). Patients were classified in the aligned group (AG) or maligned group (MG) if all the three sagittal modifiers were normal or abnormal, respectively. Patients were assessed for CD based on the following criteria: C2–C7 SVA > 4 cm, C2–C7 SVA < 4 cm, cervical kyphosis (CL > 0), cervical lordosis (CL < 0), any deformity (C2C7 SVA > 4 cm or CL > 0), and both CD (C2C7 SVA > 4 cm and CL > 0). Univariate testing was performed using t test or chi-square test, looking at the following pre-op parameters: CD, C2–C7 SVA, C2–T3 SVA, CL, T1S, T1S–CL, C2–T3 angle, LL, TK, PT, C7–S1 SVA, and PI–LL. Results A total of 184 patients met initial inclusion criteria with 70 in the AG and 34 in MG. Pre-op, patients in the MG had a higher cervical lordosis (11.7 vs. 4.9, p = 0.03), higher C2–T3 angle (13.59 vs. 4.9 p = 0.01), and higher PT ( p < 0.0001), higher SVA ( p < 0.0001), and higher PI–LL ( p < 0.0001) compared with the AG. Interestingly, the prevalence of CD at baseline was similar for both the groups: MG and AG. There was no statistically significant difference in the amount of improvement over 2 years on the ODI or the SF-36 PCS. Conclusion Patients with 2-year sagittal TL malalignment also have preoperative sagittal TL malalignment and concomitant cervical hyperlordosis as a compensatory mechanism to maintain horizontal gaze. Cervical radiographs suggestive of cervical hyperlordosis should be followed up with complete standing radiographs to asses for sagittal TL malalignment.