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The Impact of Standing Regional Cervical Sagittal Alignment on Outcomes in Posterior Cervical Fusion Surgery

Tang, Jessica A. BS*; Scheer, Justin K. BS; Smith, Justin S. MD, PhD**; Deviren, Vedat MD§; Bess, Shay MD; Hart, Robert A. MD; Lafage, Virginie PhD#; Shaffrey, Christopher I. MD**; Schwab, Frank MD#; Ames, Christopher P. MD*; the ISSG

doi: 10.1227/NEU.0b013e31826100c9
Research-Human-Clinical Studies

BACKGROUND: Positive spinal regional and global sagittal malalignment has been repeatedly shown to correlate with pain and disability in thoracolumbar fusion.

OBJECTIVE: To evaluate the relationship between regional cervical sagittal alignment and postoperative outcomes for patients receiving multilevel cervical posterior fusion.

METHODS: From 2006 to 2010, 113 patients received multilevel posterior cervical fusion for cervical stenosis, myelopathy, and kyphosis. Radiographic measurements made at intermediate follow-up included the following: (1) C1-C2 lordosis, (2) C2-C7 lordosis, (3) C2-C7 sagittal vertical axis (C2-C7 SVA; distance between C2 plumb line and C7), (4) center of gravity of head SVA (CGH-C7 SVA), and (5) C1-C7 SVA. Health-related quality-of-life measures included neck disability index (NDI), visual analog pain scale, and SF-36 physical component scores. Pearson product-moment correlation coefficients were calculated between pairs of radiographic measures and health-related quality-of-life scores.

RESULTS: Both C2-C7 SVA and CGH-C7 SVA negatively correlated with SF-36 physical component scores (r = −0.43, P < .001 and r = −0.36, P = .005, respectively). C2-C7 SVA positively correlated with NDI scores (r = 0.20, P = .036). C2-C7 SVA positively correlated with C1-C2 lordosis (r = 0.33, P = .001). For significant correlations between C2-C7 SVA and NDI scores, regression models predicted a threshold C2-C7 SVA value of approximately 40 mm, beyond which correlations were most significant.

CONCLUSION: Our findings demonstrate that, similar to the thoracolumbar spine, the severity of disability increases with positive sagittal malalignment following surgical reconstruction.

ABBREVIATIONS: CGH, center of gravity of head

HRQOL, health-related quality-of-life

NDI, neck disability index

PCSz, physical composite score

SVA, sagittal vertical axis

VAS, visual analog scale

*Department of Neurological Surgery, University of California, San Francisco, San Francisco, California

University of California, San Diego, School of Medicine, San Diego, California

§Department of Orthopedic Surgery, University of California, San Francisco, San Francisco, California

Rocky Mountain Scoliosis and Spine Center, Denver, Colorado

Department of Orthopaedic Surgery, Oregon Health and Science University, Portland, Oregon

#Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York

**Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia

Correspondence: Christopher P. Ames, MD, Department of Neurosurgery, University of California, San Francisco, Medical Center, 400 Parnassus Ave, A850, San Francisco, CA 94143. E-mail:

Received October 27, 2011

Accepted May 9, 2012

Copyright © by the Congress of Neurological Surgeons