Reliability of serial bone scintigraphy classification according to Conway in Legg-Calvé-Perthes disease

Serial bone scintigraphy in Legg-Calvé-Perthes disease (LCP) has a good early prognostic value. So far, no intra- and inter-observer reliability study on this classification has been published. Serial technetium scintigraphy of the hips was performed in 40 children with LCP disease, and the hips were classified based on their scintigraphic patterns according to Conway. Forty hips were classified twice by six observers. The two assessments were made in a different order, with a minimum time interval of one month. Unweighted kappa coefficients were calculated. Only moderate reliability was measured: intra-observer reliability: kappa = 0.573 and inter-observer reliability: kappa = 0.525. Serial bone scintigraphy in LCP has an inter- and intra-observer reliability that is only moderate. The reliability is better than that observed for the radiological Catterall classification and head-at-risk factors, but worse than the reliability of the radiological Herring classification.