RESUMO
BACKGROUND: ArbeitsgemeinschaftfürOsteosynthesefragen (AO) classification is the most frequently used tool to classify intertrochanteric fractures. However, there is limited evidence regarding its reliability. Therefore, this study was designed to evaluate inter-observer and intra-observer reliability of the AO-2018 intertrochanteric fracture classification. METHOD: A retrospective study was conducted in Imam Khomeini Hospital Complex, on radiography of patients who came with intertrochanteric fractures from March 21, 2018, to March 19, 2019. Four orthopedic trauma surgeons assessed 96 anteroposterior pelvic radiographs of intertrochanteric fractures and classified using an AO intertrochanteric fracture classification of 2018. The reading and review of radiography were performed in 2 separate occasions in a 1-month interval. The inter-observer and intra-observer reliability was assessed using kappa statistics. RESULT: The level of both mean inter-observer (K =0.322; 95%CI: 0.321-0.323) and intra-observer agreement (K =0.317; 95%CI: 0.314-0.320) in AO intertrochanteric fracture classification subgrouping were not satisfactory. The inter-observer (K =0.61; 95%CI: 0.608-0.611) and intra-observers' (K=0.560; 95%CI: 0.544-0.566) reliability in AO main groupings showed moderate agreement. CONCLUSION: The AO classification does not show adequate and acceptable inter-observer and intra-observer reliability and reproducibility. Therefore, it will be hard to base on the AO classification for treatment protocols.