Is There a Cervical Alignment Threshold Warranting Cervical Inclusion in the Construct?

BACKGROUND AND OBJECTIVES: Postoperative thoracolumbar (TL) realignment in patients with adult spinal deformity (ASD) may induce cervical spine (CS) decompensation. This study identifies predictors of CS decompensation after TL surgery and defines a baseline CS-alignment threshold based on C2-pelvic angle (C2-PA) for CS inclusion in the TL construct. METHODS: Patients with ASD undergoing TL fusion to the sacrum with an upper instrumented vertebrae at T2 or below and available baseline radiographs and patient-reported outcome measures (PROMs) were included. CS decompensation was defined as CS surgery or >2 SD above the mean in C2-PA, cervical sagittal vertical axis (cSVA), or T1-slope cervical lordosis (TS-CL) at the studied postoperative time point. RESULTS: One thousand one hundred ninety patients were included; 166 (13.9%) had CS decompensation after TL surgery, including 24 (2.0%) requiring CS extension. CS decompensation was identified in 81 patients (6.8%) at 6 weeks (4 (0.3%) extensions), 13 (1.2%) at 6 months (2 (0.2%)), 43 (3.9%) at 1 year (7 (0.6%)), and 29 (2.8%) at 2 years (11 (0.9%)). Patients with CS decompensation at 6 months showed worse global and CS alignment at 6 weeks (lumbar lordosis: 53.6 vs 46.3; cSVA: 30.5 vs 38.5; P < .05). CS decompensation at 1 year was associated with worse PROMs (physical component score: 39.0 vs 35.4; Scoliosis research society score: 3.6 vs 3.3; P < .05). CS decompensation at 2 years was associated with worse CS alignment at 1 year (TS-CL: 20.8 vs 28.6; cSVA: 31.1 vs 37.8) and worse PROMs at 2 years. Higher baseline C2-PA was associated with shorter time to CS decompensation. Cox modeling identified baseline C2-PA (hazard ratio [HR] 1.05, 95% CI, 1.03-1.06), TS-CL (HR 1.05, 95% CI, 1.03-1.06), surgical invasiveness (HR 0.99, 95% CI, 0.98-0.99), and upper thoracic instrumentation (HR 2.9, 95% CI, 1.8-4.7) as predictors of CS decompensation, with a C2-PA threshold of 26.2°. CONCLUSION: Two years after TL ASD surgery, 13.9% had CS decompensation, with 14% requiring CS extension. Baseline CS alignment independently predicted CS decompensation. Patients with preoperative C2-PA >26.2° may benefit from CS inclusion in the TL construct after external validation of this threshold by future research.

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Journal
Neurosurgery
Published
2026-10-26
DOI
https://doi.org/10.1227/neu.0000000000004264
Primary Topic
Scoliosis diagnosis and treatment
Type
article
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article

Is There a Cervical Alignment Threshold Warranting Cervical Inclusion in the Construct?

Lawrence G. Lenke, Peter Gust Passias, Mohammad Daher, Christopher Pearson Ames et al.
Neurosurgery
Scoliosis diagnosis and treatment
article

Is There a Cervical Alignment Threshold Warranting Cervical Inclusion in the Construct?

Lawrence G. Lenke, Peter Gust Passias, Mohammad Daher, Christopher Pearson Ames, Thomas J. Buell, Praveen V. Mummaneni, Bassel Georges Diebo, Breton G. Line, Christopher I. Shaffrey, Themistocles Stavros Protopsaltis, Eric O. Klineberg, Francesca Totis, Khaled M. Kebaish, Darryl Lau, Juan S. Uribe, Jeffrey Lynn Gum, Gregory M. Mundis, Richard A. Hostin, Richard G. Fessler, Shay R. Bess, Justin Kemp Scheer, Munish Chandra Gupta, Jeffrey Paul Mullin, Virginie Lafage, Jay D. Turner, Justin Smith, Stephen J. Lewis, Frank J. Schwab, David Kojo Hamilton, Robert K. Eastlack, Ricardo B. V. Fontes, Pratibha Nayak, Anthony Mikula, On behalf of the International Spine Study Group, Drew Millar, Alan H. Daniels, David Liu, Renaud Lafage, Sang Hun Lee, Dean Chou, John Moon, Han Jo Kim
article en

Abstract

BACKGROUND AND OBJECTIVES: Postoperative thoracolumbar (TL) realignment in patients with adult spinal deformity (ASD) may induce cervical spine (CS) decompensation. This study identifies predictors of CS decompensation after TL surgery and defines a baseline CS-alignment threshold based on C2-pelvic angle (C2-PA) for CS inclusion in the TL construct. METHODS: Patients with ASD undergoing TL fusion to the sacrum with an upper instrumented vertebrae at T2 or below and available baseline radiographs and patient-reported outcome measures (PROMs) were included. CS decompensation was defined as CS surgery or >2 SD above the mean in C2-PA, cervical sagittal vertical axis (cSVA), or T1-slope cervical lordosis (TS-CL) at the studied postoperative time point. RESULTS: One thousand one hundred ninety patients were included; 166 (13.9%) had CS decompensation after TL surgery, including 24 (2.0%) requiring CS extension. CS decompensation was identified in 81 patients (6.8%) at 6 weeks (4 (0.3%) extensions), 13 (1.2%) at 6 months (2 (0.2%)), 43 (3.9%) at 1 year (7 (0.6%)), and 29 (2.8%) at 2 years (11 (0.9%)). Patients with CS decompensation at 6 months showed worse global and CS alignment at 6 weeks (lumbar lordosis: 53.6 vs 46.3; cSVA: 30.5 vs 38.5; P < .05). CS decompensation at 1 year was associated with worse PROMs (physical component score: 39.0 vs 35.4; Scoliosis research society score: 3.6 vs 3.3; P < .05). CS decompensation at 2 years was associated with worse CS alignment at 1 year (TS-CL: 20.8 vs 28.6; cSVA: 31.1 vs 37.8) and worse PROMs at 2 years. Higher baseline C2-PA was associated with shorter time to CS decompensation. Cox modeling identified baseline C2-PA (hazard ratio [HR] 1.05, 95% CI, 1.03-1.06), TS-CL (HR 1.05, 95% CI, 1.03-1.06), surgical invasiveness (HR 0.99, 95% CI, 0.98-0.99), and upper thoracic instrumentation (HR 2.9, 95% CI, 1.8-4.7) as predictors of CS decompensation, with a C2-PA threshold of 26.2°. CONCLUSION: Two years after TL ASD surgery, 13.9% had CS decompensation, with 14% requiring CS extension. Baseline CS alignment independently predicted CS decompensation. Patients with preoperative C2-PA >26.2° may benefit from CS inclusion in the TL construct after external validation of this threshold by future research.

Neurosurgery
Hospital for Special Surgery (US), Brigham and Women's Hospital (US), Rush University Medical Center (US), Northwell Health (US), Barrow Neurological Institute (US), St. Joseph's Hospital and Medical Center (US), Mayo Clinic (US), Harvard University (US), Johns Hopkins University (US), University of Pittsburgh (US), Duke University (US), University of California, San Francisco (US), University of Toronto (CA), Washington University in St. Louis (US), Brown University (US), Johns Hopkins Medicine (US), Medical City Dallas Hospital (US), Lenox Hill Hospital (US), Johns Hopkins Bayview Medical Center (US), Buffalo Medical Group (US), Mayo Clinic in Arizona (US), Duke Medical Center (US), Scripps Clinic (US), Mayo Clinic in Florida (US), Johns Hopkins Hospital (US), Duke University Hospital (US), New York University Langone Orthopedic Hospital (US), Norton Leatherman Spine (US), University of Virginia (US), University at Buffalo, State University of New York (US), Columbia University (US), The University of Texas Health Science Center at Houston (US)
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Scoliosis diagnosis and treatment
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