Inter-observer and Intra-observer Reliability of Posterior Malleolus Fracture Classification Systems

Introduction The morphology of posterior malleolar fractures is recognized as an important variable in the management of ankle fractures. The classification systems for these fractures reflect morphological differences among them. In this study, we compared the inter-observer and intra-observer reliability of three classification systems for posterior malleolar fractures. Methods Forty computed tomography scans demonstrating ankle fractures with posterior malleolar components were reviewed by four reviewers on two separate occasions using the Mason and Molloy, Haraguchi, and Bartoníček classification systems. The reviewer group included two consultant foot and ankle surgeons, one foot and ankle fellow, and one specialist registrar. All members of the group were familiar with the three classification systems. We conducted a study of inter-observer and intra-observer reliability using the Fleiss kappa (κ) and mean Cohen's kappa (κ) coefficients, respectively, using R software. Results The Fleiss kappa statistic for inter-observer reliability was 0.43 (95% CI 0.35-0.50) for the Bartoníček classification, 0.65 (0.5-0.75) for the Haraguchi classification, and 0.63 (0.55-0.72) for the Mason and Molloy classification. The mean Cohen's kappa values for intra-observer reliability by classification were 0.66 (range 0.58-0.78), 0.73 (range 0.63-0.84), and 0.65 (range 0.61-0.70), respectively, for these classifications. Conclusion The Haraguchi classification had the highest inter-observer and intra-observer reliability. The inter-observer reliability agreement was substantial (0.61-0.80) for the Haraguchi classification and the Mason and Molloy classification. The Bartoníček classification demonstrated the lowest inter-observer reliability. Future research should assess the effect of these classification systems on decision-making and patient-reported outcomes.