Evaluation of Interobserver and Intraobserver Differences of Graf Method in Developmental Hip Dysplasia

Abstract

Purpose: The aim of this study was to evaluate possible differences in hip ultrasonography (US) results between physicians working in different medical centers.

Method: In this study, a total of 117 horizontal US images representing all sonographic types of developmental dysplasia of the hip (DDH) were utilized. Four experienced researchers independently measured the 117 US images at different times. The results obtained by each researcher were documented separately, including alpha and beta angles, Graf types. All of the collected data were analyzed statistically to assess for interobserver and intraobserver variability.

Results:  The study found that the average change between the alpha angles ranged from a minimum of 1 to a maximum of 4. The mean change between the beta angles was wider, ranging from a minimum of 1.8 to a maximum of 8.2. To evaluate the differences between the Graf hip typologies, paired groups were formed and Cohen's Kappa method was used. For the first group k= 0.661, for the second group k= 0.671, for the third group K= 0.647, for the fourth group k= 0, 718, k= 0.717 for the fifth group and k= 0.637 for the sixth group. Interobserver Kappa evaluation results (k=0.647) showed moderate and significant agreement.

Conclusion: The results revealed a moderate to substantial level of agreement between the researchers. Based on these findings, it was concluded that the use of US for screening and follow-up of the Graf hip typing method should be performed by experienced professionals.