Visualization of the newborn's hip joint using 3-D ultrasound and automatic image processing

Grafs method is an successful procedure for the diagnostic screening of developmental dysplasia of the hip. In a defined 2-D ultrasound (US) scan, which virtually cuts the hip joint, landmarks are interactively identified to derive congruence indicators. As the indicators do not reflect the spatial joint structure, and the femoral head is not clearly visible in the US scan, here 3-D US is used to gain insight to the hip joint in its spatial form. Hip joints of newborns were free-hand scanned using a conventional ultrasound transducer and a localizer system fixed on the scanhead. To overcome examiner-dependent findings the landmarks were detected by automatic segmentation of the image volume. The landmark image volumes and an automatically determined virtual sphere approximating the femoral head were visualized color-coded on a computer screen. The visualization was found to be intuitive and to simplify the diagnostic substantially. By the visualization of the 3-D relations between acetabulum and femoral head the reliability of diagnostics is improved by finding the entire joint geometry.