164. The reliability of the AOSpine thoracolumbar spine injury classification system in children: results of a multicenter study

Abstract

BACKGROUND CONTEXT In the adult population, there have been significant endeavors in developing classification systems of thoracolumbar injuries. These systems evolved from simple morphologic classifications to more complex systems based on fracture morphology (injury mechanism), evaluation of posterior ligamentous integrity, and neurologic status of the patient. There does not yet exist a dedicated classification system for pediatric thoracolumbar fractures despite the discordance in presentation. Pediatric thoracolumbar fractures vary in morphology, severity, and morbidity. Treatments vary from observation to surgery depending on factors such as fracture stability, displacement, and neurologic status. PURPOSE The purpose of this study was to determine if the new AOSpine thoracolumbar spine injury classification system is reliable and reproducible when applied to the pediatric population. STUDY DESIGN/SETTING Multicenter review of single institutional case series. PATIENT SAMPLE Patients under the age of 18 years who had been treated operatively for a thoracolumbar fracture between 2006 and 2016 were identified. Inclusion criteria included patients with preinjury computed tomography (CT) scans and magnetic resonance imaging (MRI) and who were less than 18 years of age. OUTCOME MEASURES Classification through AOSpine Thoracolumbar Spine Injury Classification System METHODS A group of nine POSNA (Pediatric Orthopaedic Society of North America) member surgeons were sent an electronic link containing educational videos and schematic papers describing the AOSpine Thoracolumbar Spine Injury Classification System. The link also contained MRI (magnetic resonance imaging) and CT (computed tomography) imaging of 25 pediatric patients with thoracolumbar spine injuries organized into cases to review and classify. The evaluators classified injuries into 3 primary categories: A, B, and C. Interobserver reliability was assessed for the initial reading across all 9 raters by Fleiss's kappa coefficient (kF) along with 95% confidence intervals (CI). For A and B type injuries, subclassification was conducted including A0-A4 and B1-B2 subtypes. Interobserver reliability across subclasses was assessed using Krippendorff's alpha (αk) along with bootstrapped 95% CIs. Imaging was reviewed a second time by all 9 evaluators approximately one month from the initial read. All patient imaging was blinded and randomized for each read independently. Intraobserver reproducibility was assessed for the primary classifications using Fleiss's kappa and subclassification reproducibility was assessed by Krippendorff's alpha (αk) along with 95% CIs. Interpretations for reliability estimates were based on Landis and Koch (1977): 0-0.2, slight; 0.2-0.4, fair; 0.4-0.6, moderate; 0.6-0.8, substantial; and >0.8, almost perfect agreement. RESULTS Twenty-five cases were read by 9 raters for a total of 225 initial and 225 repeated evaluations. Interobserver reliability was almost perfect (kF = 0.82; CI = 0.77 - 0.87) across all 9 raters. Subclassification reliability was substantial (αK = 0.79; CI = 0.62 - 0.90). Intraobserver reproducibility was almost perfect (kF= 0.81; CI = 0.71 - 0.90) for both primary classifications and for subclassifications (αk = 0.81; CI = 0.73 - 0.86). CONCLUSIONS The reliability for the AOSpine classification system was high amongst POSNA surgeons when applied to pediatric patients. Given a lack of a uniform classification in the pediatric population, the AOSpine Thoracolumbar Spine Injury Classification System has the potential to be used as the first universal spine fracture classification in children. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.