Postoperative coronal malalignment after adult spinal deformity surgery: incidence, risk factors, and impact on 2-year outcomes

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.

Coronal Alignment in Adult Spine Surgery

Coronal realignment is an important goal in adult spine surgery that has been overshadowed by emphasis on the sagittal plane. As coronal malalignment drives considerable functional disability, a fundamental understanding of its clinical and radiographic evaluation and surgical techniques to prevent its development is of utmost importance. In this study, we review etiologies of coronal malalignment and their radiographic and clinical assessments, risk factors for and functional implications of postoperative coronal malalignment, and surgical strategies to optimize appropriate coronal realignment in adult spine surgery.

Placement of a Kickstand Rod in Adult Spinal Deformity Surgery: A Simple 8-Step Process With Intraoperative Images and Video

BACKGROUND AND OBJECTIVES

In adult spinal deformity (ASD) surgery, operative correction of coronal malalignment remains a challenging surgical task. Given the proven effectiveness and longevity of the kickstand rod (KSR) technique and its powerful ability to correct coronal malalignment, this technique is an important tool to have available. Therefore, we sought to provide a simple 8-step description of the KSR technique using intraoperative images and video in a patient undergoing combined sagittal and coronal malalignment correction.

METHODS

A 68-year-old female with a previous history of T11-S1 posterior spinal fusion presented with mid thoracic back pain, leg paresthesias, and a right-leaning posture. The patient underwent a T4-pelvis extension of fusion, T8-11 posterior column osteotomies, and placement of a right-sided KSR to address her coronal malalignment.

RESULTS

The KSR technique is summarized in the following steps: (1) place kickstand screw, (2) place contralateral main rod and tighten all set plugs, (3) place ipsilateral main rod and keep rod long distally, (4) place a domino in the lower/mid thoracic area, (5) place the KSR and leave the rod long proximally, (6) tighten the ipsilateral main rod above the domino, (7) loosen the ipsilateral main rod below the domino, and (8) place a rod gripper below the domino and distract. Postoperatively, the coronal vertical axis improved from 4.8 to 0.6 cm, and the sagittal vertical axis improved from 9.5 to 3.9 cm.

CONCLUSION

The current case report provides a simple 8-step description of the KSR technique to improve coronal malalignment accompanied by intraoperative images and video.