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The Subaxial Cervical Spine Injury Classification System: A Novel Approach to Recognize the Importance of Morphology, Neurology, and Integrity of the Disco-Ligamentous Complex

Vaccaro, Alexander R., MD*; Hulbert, R John, MD; Patel, Alpesh A., MD; Fisher, Charles, MD§; Dvorak, Marcel, MD§; Lehman, Ronald A. Jr., MD; Anderson, Paul, MD; Harrop, James, MD*; Oner, F C., MD, PhD#; Arnold, Paul, MD**; Fehlings, Michael, MD, PhD, MD††; Hedlund, Rune, MD‡‡; Madrazo, Ignacio, MD, DSc§§; Rechtine, Glenn, MD∥∥; Aarabi, Bizhan, MD¶¶; Shainline, Mike, MS## the Spine Trauma Study Group

doi: 10.1097/BRS.0b013e3181557b92

Study Design. The classification system was derived through a literature review and expert opinion of experienced spine surgeons. In addition, a multicenter reliability and validity study of the system was conducted on a collection of trauma cases.

Objectives. To define a novel classification system for subaxial cervical spine trauma that conveys information about injury pattern, severity, treatment considerations, and prognosis. To evaluate reliability and validity of this system.

Summary of Background Data. Classification of subaxial cervical spine injuries remains largely descriptive, lacking standardization and prognostic information.

Methods. Clinical and radiographic variables encountered in subaxial cervical trauma were identified by a working section of the Spine Trauma Study Group. Significant limitations of existing systems were defined and addressed within the new system. This system, as well as the Harris and Ferguson & Allen systems, was applied by 20 spine surgeons to 11 cervical trauma cases. Six weekslater, the cases were randomly reordered and again scored. Interrater reliability, intrarater reliability, and validity were assessed.

Results. Each of 3 main categories (injury morphology, disco-ligamentous complex, and neurologic status) identified as integrally important to injury classification was assigned a weighted score; the injury severity score was obtained by summing the scores from each category. Treatment options were assigned based on threshold values of the severity score. Interrater agreement as assessed by intraclass correlation coefficient of the DLC, morphology, and neurologic status scores was 0.49, 0.57, and 0.87, respectively. Intrarater agreement as assessed by intraclass correlation coefficient of the DLC, morphology, and neurologic status scores was 0.66, 0.75, and 0.90, respectively. Raters agreed with treatment recommendations of the algorithm in 93.3% of cases, suggesting high construct validity. The reliability compared favorably to the Harris and Ferguson & Allen systems.

Conclusion. The Sub-axial Injury Classification and Severity Scale provides a comprehensive classification system for subaxial cervical trauma. Early validity and reliability data are encouraging.

The SLIC system conveys information about injury pattern and severity, as well as treatment considerations and prognosis in subaxial cervical spine injuries. Morphology of injury, disco-ligamentous complex integrity, and neurologic status are evaluated. Early data regarding validity and reliability are encouraging. Further testing is necessary before introduction into clinical practice.

From the *Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA; †University of Calgary Spine Program, Calgary, Alberta, Canada; ‡Department of Orthopaedic Surgery, University of Utah School of Medicine, Salt Lake City, UT; §Vancouver General Hospital, Vancouver, BC, Canada; ∥Department of Orthopaedics and Rehabilitation, Walter Reed Army Medical Center, Washington, DC; ¶University of Wisconsin Hospital, Madison, WI; #Univeristy of Utrecht Hospital, Utrecht, The Netherlands; **University of Kansas Hospital, Kansas City, KS; ††Toronto Western Hospital, Toronto, ON, Canada; ‡‡Huddinge University Hospital, Stockholm, Sweden; §§Department of Neurosciences, Hospital Ángeles del Pedregal, Mexico City, Mexico; ∥∥University of Rochester, Rochester, NY; ¶¶University of Maryland, Baltimore, MD; and ##PhDx Systems, Albuquerque, NM.

Acknowledgment date: November 21, 2006. First revision date: March 6, 2007. Acceptance date: March 7, 2007.

Supported by the Spine Trauma Study Group and funded by an educational/research grant from Medtronic Sofamor Danek.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the United States Army or the Department of Defense. One author is an employee of the United States government. This work was prepared as part of his official duties and as such, there is no copyright to be transferred.

Address correspondence and reprint requests to Alexander R. Vaccaro, MD, Rothman Institute, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107-4216; E-mail:

© 2007 Lippincott Williams & Wilkins, Inc.