Reliability of a classification of fractures of the hand based on the AO comprehensive classification system.

The AO/ASIF Comprehensive Classification of Fractures is a logical system to describe and compare long-bone fractures. We adapted this classification to the hand to classify fractures of the metacarpals and phalanges. The alphanumeric sequence codes the bone involved, the bone segment, and the fracture type. To assess the reliability of this classification, one hundred radiographs of hand fractures were classified by nine observers in four sessions. Using Cohen's kappa coefficient, overall inter-observer agreement was 0.93 for bone identification, 0.80 for bone segment, and 0.44 for fracture type. Corresponding intra-observer agreement was 0.94, 0.92 and 0.62 respectively.