The Ischial Spine in Developmental Hip Dysplasia: Unraveling the Role of Acetabular Retroversion in Periacetabular Osteotomy

Figure 6

Simplified hip illustrations explaining the possible mechanisms of retroversion: acetabular walls variation versus axial rotation of the pelvis. The arrow depicts the direction of AP pelvic radiographs projection. The hip at the top right is a simulation of an AP pelvic X-ray showing the COS and PRISS for each corresponding setting where the anterior and posterior (green and blue dashed lines, respectively) acetabular walls are outlined. COS = crossover sign; PRISS = prominence of the ischial spine sign.