INTER- AND INTRAOBSERVER DIFFERENCES IN THE ASSESSMENT OF HIP ULTRASONOGRAPHY (GRAF METHOD)

Abstract

Introduction. In Mid-Europe developmental dysplasia of the hip (DDH) is diagnosed using the sonographic hip screening described by Graf. To learn the necessary standards three courses are mandatory. However, little is known about learning curves and measurement errors of doctors at different levels of training and experience.

Material and Methods. Between 1997 and 2002 participants of the basic, advanced and final hip ultrasonogra-phy course were evaluated by a questionnaire and 34 normal and pathological sonograms. They were asked to measure the alpha and beta angle. “Normal” angles of each hip were created through the mean values of two experienced course organizers.

Results. 186 doctors (40% orthopedic surgeons, 60% pediatricians) were evaluated. The group included 20% interns, 60% residents and 20% consultants. An average time of 6.3 months lay between the basic and the advanced, and of 16.7 months between the advanced and the final course. The evaluation of the sonograms according to Graf showed major inter-observer differences of up to 30°. Participants had more difficulties in evaluating a correct beta angle than an alpha angle. Sonographic pictures of minor quality and pathological hips produced more difficulties than pictures of Graf type I and II hips. In the basic course all measurements showed an average difference of 3,6°, in the advanced course of 3,1° and in the final course of 4,2°. The number of examinations between courses did not correlate with good measurements.

Conclusion. Even participants of all three courses seem to develop major systemic errors if ultrasonography is regularly applied without supervision. Therefore, regular training and supervision should be mandatory in order to guarantee good quality.