[Principles of sonographic examination of the hip].

The advantages of ultrasound in the diagnosis of congenital dislocation and dysplasia of the hip, compared with other imaging diagnostical methods are obvious, since an exact and early diagnosis of hip immaturity can be made. Using realtime sonography, it is possible to directly visualise the motion of the femoral head in the acetabulum and verify any instability of the joint. Especially hips which are classified as being in the critical range should always be examined dynamically to judge their grade of instability. This is necessary because these hips often show no pathology when examined clinically. Unlike radiography, hip sonography can diagnose the grade of hip maturation from the day of birth. Newborn screening can thus result in early detection and treatment of pathological hip joints. Since introducing routine newborn screening at our hospital, we have been able to achieve an earlier onset of therapy in 80% of the cases, within the first four weeks of age. The percentage of CDH diagnosed before and after introducing the newborn screening did not differ. Babies which are classified as being in the "risk group" were followed up regularly. Subsequent to the dynamic examination of the hip, problems of describing the arthrosonographic anatomy of the hip are discussed.