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The Comprehensive Anatomical Spinal Osteotomy Classification

Schwab, Frank MD*; Blondel, Benjamin MD*,‡; Chay, Edward BA*; Demakakos, Jason MS*; Lenke, Lawrence MD§; Tropiano, Patrick MD; Ames, Christopher MD; Smith, Justin S. MD, PhD; Shaffrey, Christopher I. MD; Glassman, Steven MD#; Farcy, Jean-Pierre MD**; Lafage, Virginie PhD*

doi: 10.1227/NEU.0000000000000182o
Research-Laboratory:Editor' Choice
Editor's Choice

BACKGROUND: Global sagittal malalignment is significantly correlated with health-related quality-of-life scores in the setting of spinal deformity. In order to address rigid deformity patterns, the use of spinal osteotomies has seen a substantial increase. Unfortunately, variations of established techniques and hybrid combinations of osteotomies have made comparisons of outcomes difficult.

OBJECTIVE: To propose a classification system of anatomically-based spinal osteotomies and provide a common language among spine specialists.

METHODS: The proposed classification system is based on 6 anatomic grades of resection (1 through 6) corresponding to the extent of bone resection and increasing degree of destabilizing potential. In addition, a surgical approach modifier is added (posterior approach or combined anterior and posterior approaches). Reliability of the classification system was evaluated by an analysis of 16 clinical cases, rated 2 times by 8 different readers, and calculation of Fleiss kappa coefficients.

RESULTS: Intraobserver reliability was classified as “almost perfect”; Fleiss kappa coefficient averaged 0.96 (range, 0.92-1.0) for resection type and 0.90 (0.71-1.0) for the approach modifier. Results from the interobserver reliability for the classification were 0.96 for resection type and 0.88 for the approach modifier.

CONCLUSION: This proposed anatomically based classification system provides a consistent description of the various osteotomies performed in spinal deformity correction surgery. The reliability study confirmed that the classification is simple and consistent. Further development of its use will provide a common frame for osteotomy assessment and permit comparative analysis of different treatments.

ABBREVIATIONS: P, posterior approach

A/P, combined anterior and posterior approaches

PSO, pedicle subtraction osteotomy

*NYU Hospital for Joint Diseases, New York, New York;

Orthopedic Department, Aix-Marseille University, Marseille, France;

§Washington University School of Medicine, St. Louis, Missouri;

Neurosurgery, University of California San Francisco, San Francisco, California;

Neurological Surgery, University of Virginia, Charlottesville, Virginia;

#Spine Institute for Special Surgery, University of Louisville, Kentucky;

**Maimonides Medical Center, New York, New York

Correspondence: Virginie Lafage, PhD, NYU Hospital for Joint Diseases, 306 E, 15th St, Suite 1F, New York, NY 10003. E-mail:

Received April 22, 2013

Accepted September 17, 2013

Copyright © by the Congress of Neurological Surgeons