CLINICAL ARTICLE J Neurosurg Spine 25:303–308, 2016 S UBAXIAL cervical spine trauma (SCST) comprises injuries from C-3 to C-7. 1,24 More than 50% of the fractures in this region affect the C5–7 segments, likely due to the greater mobility in this region. 6,15 Spinal cord injury (SCI) in the subaxial cervical spine has a high rate of morbidity, as it is associated with a higher risk of tetraplegia and important functional disability, with a sig- nificant economic and social impact. 3,12,18,23,24 Historically, many SCST classifications have been pro- posed. None has achieved widespread acceptance due to different limitations and drawbacks. Allen et al. proposed a classification of cervical fractures that divided injuries into 8 groups based on the mechanism of trauma. 1 The re- liability and complexity of this system were key disadvan- tages. Another system proposed by Magerl et al. adapted the AOSpine thoracolumbar system to the cervical spine. Injuries were classified into 3 main groups, according to their mechanism: Type A (compression), Type B (distrac- tion), and Type C (rotation) injuries. 9 The criticism of this complex classification system was that it did not take into account the neurological status, and it did not guide treat- ment. 6,7,15 ABBREVIATIONS AIS = American Spinal Injury Association Impairment Scale; SCI = spinal cord injury; SCST = subaxial cervical spine trauma; SLIC = Subaxial Cervical Spine Injury Classification. SUBMITTED August 30, 2015. ACCEPTED February 11, 2016. INCLUDE WHEN CITING Published online April 22, 2016; DOI: 10.3171/2016.2.SPINE151039. Evaluation of the reliability and validity of the newer AOSpine subaxial cervical injury classification (C-3 to C-7) Otávio Turolo da Silva, MD, 1 Marcelo Ferreira Sabba, MD, 1 Henrique Igor Gomes Lira, MD, 1 Enrico Ghizoni, MD, PhD, 2 Helder Tedeschi, MD, PhD, 1 Alpesh A. Patel, MD, 2 and Andrei Fernandes Joaquim, MD, PhD 1 1 Department of Neurology, University of Campinas, Campinas, São Paulo, Brazil; and 2 Department of Orthopedics, Northwestern University, Chicago, Illinois OBJECTIVE The authors evaluated a new classification for subaxial cervical spine trauma (SCST) recently proposed by the AOSpine group based on morphological criteria obtained using CT imaging. METHODS Patients with SCST treated at the authors’ institution according to the Subaxial Cervical Spine Injury Clas- sification system were included. Five different blinded researchers classified patients’ injuries according to the new AOSpine system using CT imaging at 2 different times (4-week interval between each assessment). Reliability was as- sessed using the kappa index (k ), while validity was inferred by comparing the classification obtained with the treatment performed. RESULTS Fifty-one patients were included: 31 underwent surgical treatment, and 20 were managed nonsurgically. Intraobserver agreement for subgroups ranged from 0.61 to 0.93, and interobserver agreement was 0.51 (first assess- ment) and 0.6 (second assessment). Intraobserver agreement for groups ranged from 0.66 to 0.95, and interobserver agreement was 0.52 (first assessment) and 0.63 (second assessment). The kappa index in all evaluations was 0.67 for Type A, 0.08 for Type B, and 0.68 for Type C injuries, and for the facet modifier it was 0.33 (F1), 0.4 (F2), 0.56 (F3), and 0.75 (F4). Complete agreement for all components was attained in 25 cases (49%) (19 Type A and 6 Type C), and for subgroups it was attained in 22 cases (43.1%) (16 Type A0 and 6 Type C). Type A0 injuries were treated conservatively or surgically according to their neurological status and ligamentous status. Type C injuries were treated surgically in almost all cases, except one. CONCLUSIONS While the general reliability of the newer AOSpine system for SCST was acceptable for group clas- sification, significant limitations were identified for subgroups. Type B injuries were rarely diagnosed, and only mild (Type A0) and extreme severe (Type C) injuries had a high rate of interobserver agreement. Facet modifiers and intermediate injury patterns require better descriptions to improve their low agreement in cases of SCST. http://thejns.org/doi/abs/10.3171/2016.2.SPINE151039 KEY WORDS cervical trauma; classification; evaluation; reliability; subaxial cervical spine; treatment ©AANS, 2016 J Neurosurg Spine Volume 25 • September 2016 303 Unauthenticated | Downloaded 05/18/22 01:48 AM UTC