Technical errors in the application of Graf's hip sonography method.

Aim: The aim of the study is to point out possible examination errors becau se of a titled transducer, and to analyse their sources. Methods: The resul ts obtained by experienced examiners using the correct examination techniqu e were compared to results obtained under defined deviations from the stand ard. With the use of a computer model the course taken by the ultrasound wa ves in the neonatal hip was simulated and the sonographic image reconstruct ed. Results: Twisted as well as tilted positions of the transducer lead to significant errors in ct, the acetabular roof angle. This is in accordance with the computer model predictions. Caudo-cranially tilted probes lead to false-positive, therapeutically relevant incorrect diagnoses. Conclusion: T he computer simulation predicts a high degree of accuracy of hip sonography in Graf's technique under standard conditions. The effectiveness of sonogr aphic infant hip screening largely depends on the ability to adhere to the standardized approach, minimizing possible errors. A mechanical transducer guide prevents tilting errors by reducing the degrees of variability in pos itioning the transducer.