Posterior Malleolar Fracture Assessment: An Independent Interobserver and Intraobserver Validation of Three Computed Tomography-Based Classifications

Posterior malleolus fractures occur in up to 50% of all ankle fractures. Several classification systems exist for their characterization, especially under CT. However, those classifications do not report the level of agreement or do it incompletely. This study aims to independently assess three posterior malleolus fracture classifications (Haraguchi, Bartoníček/Rammelt, and Mason). METHODS: This study was designed according to the Guidelines for Reporting Reliability and Agreement Studies. Ninety-four CT scans of patients with ankle fractures that had posterior malleolus fractures were included. Posterior malleolus fractures were assessed by six evaluators (three attending foot and ankle surgeons and three orthopaedic surgery residents) according to Haraguchi, Bartoníček/Rammelt, and Mason classifications. All images were reassessed by the same evaluators in a random sequence 3 weeks later. The kappa (k) coefficient was used to determine the interobserver and intraobserver agreement. Statistical significance was established using P < 0.05 with a 95% confidence interval (CI). RESULTS: The interobserver agreement was moderate for Haraguchi, Bartoníček/Rammelt, and Mason classifications with a global k value of 0.52 (95% CI, 0.43 to 0.60), 0.53 (95% CI, 0.46 to 0.61), and 0.54 (95% CI, 0.47 to 0.62), respectively. The intraobserver agreement was substantial for Haraguchi, Bartoníček/Rammelt, and Mason classifications, with an overall k value of 0.70 (95% CI, 0.64 to 0.74), 0.73 (95% CI, 0.68 to 0.78), and 0.73 (95% CI, 0.69 to 0.78), respectively. Interobserver and intraobserver agreement among orthopaedic surgeons and residents had no significant difference. CONCLUSION: The current classifications for posterior malleolus fractures showed a substantial intraobserver agreement. Nevertheless, the interobserver agreement obtained was just moderate for all classifications, independent of the level of expertise of the evaluators.