• Hey Hwee Weng Dennis HWD University Orthopaedics, Hand and Reconstructive Microsurgery (UOHC), National University Health System, 1E Kent Ridge Rd, NUHS Tower Block Level, Cheung-Kue Kim, Won-Gyu Lee, Hyung-Suk Juh, and Ki-Tack Kim.
• University Orthopaedics, Hand and Reconstructive Microsurgery (UOHC), National University Health System, 1E Kent Ridge Rd, NUHS Tower Block Level 11, Singapore 119228, Singapore.
• Spine J. 2017 Dec 1; 17 (12): 1837-1845.

Background ContextThe aim of spinal deformity correction is to restore the spine's functional alignment by balancing it in both the sagittal and coronal planes. Regardless of posture, the ideal coronal profile is straight, and therefore readily assessable.PurposeThis study compares two radiological methods to determine which better predicts postoperative standing coronal balance.Study Design/SettingWe conducted a single-center, radiographic comparative study between 2011 and 2015.Patient SampleA total of 199 patients with a mean age of 55.1 years were studied. Ninety patients with degenerative lumbar scoliosis (DLS) and 109 ankylosing spondylitis (AS) were treated with posterior surgery during this period.Outcome MeasuresBaseline clinical and radiographic parameters (sagittal and coronal) were recorded. Comparison was performed between the new supra-acetabular line (central sacral vertical line [CSVL1]) and conventional supra-iliac line (CSVL2) perpendicular methods of coronal balance assessment. These methods were also compared with the gold standard standing C7 plumb line.MethodsEach patient underwent standardized operative procedures and had perioperative spine X-rays obtained for assessment of spinal balance. Adjusted multivariate analysis was used to determine predictors of coronal balance.ResultsSignificant differences in baseline characteristics (age, gender, and radiographic parameters) were found between patients with DLS and AS. CSVL1, CSVL2, and C7 plumb line differed in all the perioperative measurements. These three radiological methods showed a mean right coronal imbalance for both diagnoses in all pre-, intra-, and postoperative radiographs. The magnitude of imbalance was the greatest for CSVL2 followed by CSVL1 and subsequently the C7 plumb line. A larger discrepancy between CSVL and C7 plumb line measurements intraoperatively than those postoperatively suggests a postural effect on these parameters, which is greater for CSVL2. Multivariate analysis identified that in DLS, the preoperative C7 plumb line was predictive of its postoperative value. CSVL1, but not CSVL2, was predictive of the postoperative C7 plumb line in patients with AS.ConclusionsThe supra-acetabular line (CSVL1) is better, although not ideal, as compared with the supra-iliac line (CSVL2) in determining coronal balance. Because CSVL1 still cannot be relied on with a high predictive value, it is imperative that future studies continue to identify better intraoperative markers for achieving coronal balance.Copyright © 2017 Elsevier Inc. All rights reserved.

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