The standard plane of Graf - A "standard sector"? Ultrasound examination of anatomic preparations of infant hips

Aim: To answer the question as to which ultrasound sections, related to the hip joint plane, lead to pictures of the so-called "standardplan" of Graf, anatomic preparations of infant hips were examined by ultrasound. Method: 10 anatomic preparations of infant hips were fixed in a support which allow s an exact positioning of the ultrasound plane related to the acetabular in let plane in a water bath. The joints were examined while changing the rela tive position in steps of 10 degrees. The ultrasound images were documented by videoprint and the alpha -angles were measured if the criterias of the standard plane were fulfilled. Results: In order to obtain images that are analysable by the method of Graf, the ultrasound beam has to intersect with the acetabular inlet plane at defined angles. The acetabular notch has to be anteriorly rotated from the ultrasound beam plane by at least 20 degrees . Beam entry within a 50-degree sector posterior to the perpendicular on th e inlet plane gave analysable images. The alpha -angles were markedly affec ted by coronal-plane transducer tilt. Caudad tilts were associate with lowe r values, a fact that should be borne in mind in clinical ultrasound invest igations. Conclusion: The "standard plane" of graf is a "standard sector", which can be defined in all three dimensions. The relations between the ace tabular inlet plane and the sonographic beam are described exactly for the first time. The results are important because of their influence on clinica l ultrasound examinations.