Neutral pelvic positioning during recording of anteroposterior pelvic radiographs has been recommended for precise interpretation
of acetabular deformities. Because the effect of pelvic positioning is controversial in the literature, we asked whether the
weightbearing position would alter radiographic interpretations. We obtained sets of supine and weightbearing anteroposterior
pelvic radiographs of 31 patients with developmental dysplasia of the hip and measured pelvic tilt, acetabular version, center
edge angle, acetabular index, joint space width and femoral head translation. For both genders the pelvis extended when patients
were repositioned from supine to weightbearing but extension was more pronounced in women compared with men. The number of
patients with apparent acetabular retroversion was reduced from 11 supine to four when weightbearing. The center edge angle,
acetabular index, joint space width and femoral head translation were similar in both views. We recommend weightbearing anteroposterior
pelvic radiographs be obtained to assess DDH given the differences in pelvic flexion-extension and interpretations of acetabular
version.
Level of Evidence: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the human protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research.