Comparison of the Reliability and Agreement of Böhler and Gissane Angle Measurements Using PACS and ImageJ

Background Böhler’s and Gissane’s angles are used in calcaneal fracture assessment, but measurement consistency varies. ImageJ may offer a low-cost alternative to Picture Archiving and Communication System (PACS). This study aimed to define margin of error (MOE) and evaluate whether ImageJ provides measurement agreement and reliability comparable to PACS Methods Margin of error was predefined based on previously reported variability and expert consensus. Three observers measured Böhler’s and Gissane’s angles on 42 radiographs using PACS and ImageJ; a consensus PACS measurement served as the reference measurement. Reliability (intraclass correlation coefficient), deviation from the consensus reference (mean/median absolute error; bias), agreement within MOE, and Bland-Altman analyses were performed. Results The predefined margins of error were ±2.5° (Böhler) and ±5° (Gissane). Interobserver reliability was good to excellent for Böhler and poor to moderate for Gissane. Within-observer inter-method agreement was excellent for Böhler and variable for Gissane. Deviations for Gissane frequently exceeded the MOE, with minimal method bias. Conclusion ImageJ performed comparably to PACS for Böhler’s angle measurements. However, Gissane’s angle demonstrated poor reproducibility with both methods, likely due to anatomical and projectional factors. Level of evidence: Diagnostic, level III