Comparison of the Odontoid and Orbital–Coronal Vertical Axis Lines in Evaluating Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery

Study Design. Asymptomatic Multi-Ethnic Alignment Normative Study (MEANS) cohort: cross-sectional, multicenter. Symptomatic cohort: retrospective, multisurgeon, single-center. Objective. To assess the association of odontoid–coronal vertical axis (OD-CVA) and orbital–coronal vertical axis (ORB-CVA) with radiographic parameters, patient-reported outcomes, and clinical outcomes. Summary of Background Data. Previous literature studied the OD-CVA in an asymptomatic cohort and ORB-CVA in a symptomatic cohort, demonstrating their correlations with radiographic parameters and ORB-CVA with outcomes. Materials and Methods. A total of 468 asymptomatic adult participants were prospectively enrolled in the MEANS cohort. 174 symptomatic patients with adult spinal deformity with ≥6 fused levels and 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. The association between OD-CVA and ORB-CVA, and radiographic parameters, perioperative variables, PROs, and outcomes were analyzed. Pearson correlation was used to assess correlation and logistic regression odds of outcomes. Results. In the MEANS cohort, the ORB-CVA correlated with C7-CVA ( r = 0.58) and OD-CVA ( r = 0.74). In the symptomatic cohort, preoperative ORB-CVA correlated better with leg length discrepancy; r = 0.17, P = 0.029), whereas preoperative OD-CVA correlated better with C7-CVA ( r = 0.90, P < 0.001). Postoperative ORB-CVA correlated with postoperative C7-CVA ( r = 0.66, P < 0.001), and postoperative OD-CVA correlated strongly with postoperative C7-CVA ( r = 0.81, P < 0.001). Both preoperative OD-CVA ( r = 0.199) and ORB-CVA ( r = 0.208) correlated with the preoperative Oswestry Disability Index. ORB-CVA correlated better than OD-CVA in the preoperative Scoliosis Research Society-22r pain category but worse in total and other subcategories. Preoperative ORB-CVA was associated with increased odds of intraoperative complication (odds ratio = 1.28, 1.01–1.22), like OD-CVA (odds ratio = 1.30, 1.12–1.53). Neither preoperative ORB-CVA nor OD-CVA was associated with reoperations and readmissions after multivariate analysis. Preoperative OD-ORB mismatch >1.5 cm was not associated with increased odds of intraoperative and postoperative complications, reoperations, or readmissions. Conclusion. ORB-CVA and OD-CVA correlated with radiographic parameters, patient-reported outcomes, and intraoperative complications. ORB-CVA and OD-CVA can be used interchangeably as cranial coronal parameters in adult spinal deformity surgery.