The effect of pediatric orthopaedic experience on interobserver and intraobserver reliability of the herring lateral pillar classification of Perthesdisease

An analysis was done of the effect of surgeons' pediatric orthopaedic exper ience on the classification of Perthes disease according to the lateral pil lar classification described by Herring. Five observers with varied pediatr ic orthopaedic experience reviewed anteroposterior (AP) pelvis radiographs of 33 patients in the fragmentation phase of Perthes disease and classified each case on three separate occasions at least 24 hours apart. Frog-leg la teral-view radiographs taken at the same time were also classified using th e same criteria based on the femoral head anterior column. Kappa statistics showed good agreement for intra- and interobserver reliability of classifi cation for both AP and frog lateral radiographs. There, were no statistical ly significant variations among the reviewers. Twenty-four percent of the c ases had a classification one grade worse on the lateral radiograph compare d to the AP view. The lateral pillar classification provides a reproducible radiographic technique for Perthes disease characterization independent of pediatric orthopaedic experience.