[The assessment of changes in radiological parameters of acetabulum of the hip joint according to position of the pelvis].

The aim of the study was to analyze the repeatability of selected radiological parameters in the assessment of mild forms of developmental dysplasia of the hip and to evaluate the changes of the parameters according the position of the pelvis. Retrospective review of radiographs of 98 hips (49 children) was done in antero-posterior and Lauenstein position. Among them 59 hips were treated for type II hip dysplasia according to Graf. At the latest follow-upthe mean age was 9.1 years (range from 4 to 15 years). On radiographs in antero-posterior position of the hips mean rotation index (Tönnis-Brunken index) was 1.0, and on radiographs in Lange position was 0.98 and had no influence on measured parameters. On radiographs in antero-posterior position pelvis was more in forward rotation than in Lange position. With the pelvis in more forward rotation (measured using Ball-Kommend index) the value of Lequesne and Ullmanna-Sharp angles were decreased and Wiberg angle was increased. The angles had good repeatability. The other parameters: acetabular index, decentration distance and Idelberg-Frank angle were not statistically related to Ball-Kommend index. Idelberg-Frank angle had satisfactory repeatability but acetabular index and decentration distance had poor repeatability. Considering above mentioned characteristics of Idelberg-Frank angle, this parameter may be a useful tool for assessment of the hip.