Comparison of the interobserver reliability of ultrasonography and radiography in diagnosis of developmental dysplasia of the hip

Abstract

We aimed to compare the interobserver reliability of ultrasonography (USG) and x-ray (XR) and to calculate the sensitivity and specificity of these tests in the diagnosis of developmental dysplasia of the hip (DDH). This retrospective study was conducted among 150 USG and 300 XR images of infants examined for DDH between January 2013 and June 2015. The sonographic angle measurements and hip classifications of each USG and XR were carried out by five orthopedic surgeons specialized in pediatric orthopedics. Both USG and XR showed almost perfect agreement between five observers (κUSG=0.936, κXR=0.927, respectively, p<.0001). In patients under the age of 6 months, the interobserver reliability was almost perfect for USG and substantial for XR (κUSG=0.957, κXR=0.809, respectively, p<.0001). In patients older than 6 months, although interobserver agreement of both tests were almost perfect (κ>0.81), XR showed slightly higher agreement than USG (κXR=0.912, κUSG=0.885, respectively, p<.0001). In the diagnosis of DDH, both USG and plain x-rays are effective radiological tests because they offer high interobserver reliability. However, the surgeon's practical training and experience significantly affect the reliability in the evaluation of pediatric hip USG and XR.