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: firstname.lastname@example.org
Received April 22, 2013
Accepted September 17, 2013