Interobserver and intraobserver variation in classification systems for fractures of the distal humerus.
Wainwright AM., Williams JR., Carr AJ.
We assessed the inter- and intraobserver variation in classification systems for fractures of the distal humerus. Three orthopaedic trauma consultants, three trauma registrars and three consultant musculoskeletal radiologists independently classified 33 sets of radiographs of such fractures on two occasions, each using three separate systems. For interobserver variation, the Riseborough and Radin system produced 'moderate' agreement (kappa = 0.513), but half of the fractures were not classifiable by this system. For the complete AO system, agreement was 'fair' (kappa = 0.343), but if only AO type and group or AO type alone was used, agreement improved to 'moderate' and 'substantial', respectively (kappa = 0.52 and 0.66). Agreement for the system of Jupiter and Mehne was 'fair' (kappa = 0.295). Similar levels of intraobserver variation were found. Systems of classification are useful in decision-making and evaluation of outcome only if there is agreement and consistency among observers. Our study casts doubt on these aspects of the systems currently available for fractures of the distal humerus.