[Value of angle measurements in hip sonography. Methodological and technical analysis].

The Graf classification of sonographic hip-studies is based upon angle-measurements. 167 patients have been examined and evaluated in a double-blind study of the reproducibility of these measurements and the resulting classification. The resulting ranges for the different types were compared with the values given by Graf. The influence of the investigator, the interpreter and of the chosen section plane were analysed and compared with the difference in classifying based upon visual impression. The global impression of the operator proves to be the most reliable basis for interpreting the ultrasound study (variation of 6%), while the measured angle beta (+/- 35% deviation) seems not to be as useful.