The influence of surgeon experience and subspeciality on the reliability of the AO spine sacral classification system

Study Design: Cross-sectional survey Objective: To determine the influence of surgeons’ level of experience and subspeciality training on the reliability, reproducibility, and accuracy of sacral fracture classification using the AO Spine Sacral Injury Classification System. Summary of Background Data: An ideal classification system is easily comprehensible and reliable amongst the diverse group of surgeons. A surgeons’ level of experience may have a significant effect on the reliability and accuracy of a classification system. Moreover, surgeons of different subspecialities may have various levels of comfort with imaging assessment of sacral injuries required for accurate diagnosis and classification. Methods: High-resolution computerized tomography (CT) images from 26 cases were assessed by 172 investigators from a diverse array of surgical subspecialities (general orthopaedics, neurosurgery, orthopaedic spine, orthopaedic trauma) and experience (<5, 5-10, 11-20, >20 years). Validation assessments were performed via web conference using high-resolution images, as well as axial/sagittal/coronal CT scan sequences. Two assessments were performed by each investigator independently three weeks apart in randomized order. Reliability and reproducibility were calculated with cohen’s kappa coefficient (k) and gold standard classification agreement was determined for each fracture morphology and subtype and stratified by experience and subspeciality. Results: Respondents achieved an overall k = 0.87 for morphology and k = 0.77 for subtype classification, representing excellent and substantial intraobserver reproducibility, respectively. Respondents from all four practice experience groups demonstrated excellent interobserver reliability when classifying overall morphology (k=0.842/0.850, Assessment 1/Assessment 2) and substantial interobserver reliability in overall subtype (k=0.719/0.751) in both assessments. General orthopaedists, neurosurgeons, and orthopaedic spine surge