[Hip ultrasonography. Basic principles and current aspects].

Hip sonography is the subject of controversial discussion in several countries. This is because of the different demands made on the diagnosis. In principle the techniques described by Harke, Terjesen and Suzuki are satisfied by a differentiation of luxation from non-luxated joints. An evaluation of the hyalin cartilaginous preformed acetabular roof does not exist. Physiological variations dependent on age cannot be differentiated from real dysplasias by the techniques mentioned above. The sonographic examination technique in German-speaking countries evaluates the maturation of the joint and quantifies the cartilage and the bony acetabular roof. Additionally, this coverage is seen in relation to the age, and the deformation of the acetabulum in luxated joints is analysed. Physiological elastic deflection of the hyalin cartilaginous part of the acetabulum can be separated from real instability signs. Oblique positions of the probe during examination of the baby can lead to diagnostic errors, so special examination techniques have to be used. 3D-sonograms may improve the diagnostic possibilities. A general screening of newborns in use in Austria since 1992 has demonstrated that the rate of treatment can be decreased by about 50% and sonography, used correctly, can avoid overtreatment.