Distal radius fractures are difficult to classify

Abstract Background Traditionally, distal radius fractures (DRFs) have been described using eponyms, e.g. Colles, Smith, Barton, Chauffeur. During the last half of the 20 th century several classification systems for DRF have emerged. We evaluated the inter- and intra-observer agreement of the AO/OTA, Frykman and Older classification systems. Methods Four observers, an intern, an orthopaedic registrar, an orthopaedic consultant and a radiology consultant, independently evaluated DRF radiograms and classified the fractures according to the AO/OTA, Frykman and Older classification systems. After an interval of 6 months, radiograms of 30 randomly chosen patients were re-evaluated by the same observers. Results Radiograms of 573 DRF patients were evaluated in the study. The inter-observer reliability of the AO/OTA fracture types (A, B and C) was ‘weak’ (kappa = 0.45). The agreement dropped to ‘minimal’ (kappa = 0.24) regarding the AO/OTA groups (A2, A3, B1, B2, B3, C1, C2 and C3). The reliability of the Frykman classification system was ‘weak’ (kappa = 0.41), and we observed the lowest inter-observer reliability for the Older classification system (kappa = 0.10). The kappa values for the intra-observer reproducibility of the AO/OTA fracture types (A, B and C) ranged from 0.58 to 0.87. For the AO/OTA groups (A2, A3, B1, B2, B3, C1, C2 and C3) the reproducibility was lower ranging from ‘minimal’ to ‘weak’. The intra-observer reproducibility of the Frykman system was ‘weak’ to ‘moderate’ and even worse for the Older classification system. Conclusion Based on these findings the AO/OTA classification system seems to be most reliable for routine use, however, with lower kappa values concerning the agreement for the groups. The Frykman and Older classification systems cannot be recommended because of less convincing results.