Ultrasound Screening of the Infantʼs Hip: Introduction of a New Combined Angle

This study evaluates the most widely used sonographic measurements for judging an infant's hip morphology. The α and β angles of Graf, the bony coverage percentage of Morin and a new combined angle were analysed. This latter angle records the direction of the whole acetabulum (cartilagenous and bony) as one unit. One-hundred sonograms were examined independently by two observers to calculate the interobserver and intraobserver limits of agreement. The new combined angle proved to be the most reproducible measurement. Graf's α angle was the second most reliable measurement followed by the bone coverage percentage. The relationship between the combined angle and α angle was statistically significant with a correlation coefficient of 0.70 (P <0.001).