Inter- and intraobserver reliabilities and critical analysis of the osteoporotic fracture classification of osteoporotic vertebral body fractures

Purpose The Osteoporotic Fracture Working Group (Spine Division of the German Orthopaedic and Trauma Society) has developed a classification system for osteoporotic thoracolumbar fractures, namely the osteoporotic fracture (OF) classification system. The purpose of this study was to determine the inter- and intraobserver reliabilities of the OF classification system for osteoporotic vertebral body fractures (VFs) at a level-one trauma centre. Methods Conventional radiography, magnetic resonance imaging (MRI), and computed tomography (CT) scans of 54 consecutive women who sustained an osteoporotic VF were analysed by six orthopaedic traumatologists with varying levels of experience. The inter- and intraobserver reliabilities of the OF classification system were determined using intraclass correlation coefficients (ICCs) and Cohen's kappa. Results The overall interobserver reliability of the OF classification system was good (ICC, 0.62 [0.51, 0.72]). The intraobserver reliability was found to be substantial (overall weighted Cohen's kappa estimate [95% confidence interval {CI}] = 0.74 [0.67, 0.80]) and better when the radiography, MRI, and CT scans were assessed together than when only the radiography and MRI scans were evaluated, although the difference was not significant. Conclusion The OF classification system is easy to use. It shows good interobserver reliability and substantial intraobserver reliability if diagnostic prerequisites (conventional radiography, MRI, and CT scans) are met.