We investigated the version and morphological features of the acetabulum using pelvic radiographs and computed tomography images of ninety-six hips in fifty-nine patients with developmental dysplasia of the hip. A diagnosis of acetabular retroversion was based on the presence of a positive cross-over sign on the pelvic radiograph. Using computed tomography images, we determined the acetabular anteversion angle at various levels in the axial plane. The acetabular sector angle served as an indicator of acetabular coverage of the femoral head. We evaluated the association between acetabular version and the patient's age at the onset of pain. Fifty normal hips were examined as controls. Results: We observed acetabular retroversion in 18% (seventeen) of the ninety-six hips in the patients with developmental dysplasia of the hip. The mean acetabular anteversion angle in the hips with acetabular retroversion was significantly smaller, at all levels, than that in the hips with acetabular anteversion; this tendency was more evident at proximal levels. There was significantly less posterior and posterosuperior coverage in the hips with acetabular retroversion than in those with acetabular anteversion, but superior acetabular coverage did not differ between the groups. Multivariate analysis showed that the onset of pain occurred at a significantly earlier age in patients with acetabular retroversion (27.9 years) than in those with acetabular anteversion (40.5 years), regardless of the severity of the dysplasia (p = 0.003). Conclusions: In patients with developmental dysplasia of the hip, acetabular retroversion results from relatively deficient coverage by the posterior portion of the acetabulum. Developmental dysplasia with acetabular retroversion is associated with an earlier onset of pain than is developmental dysplasia with anteversion, suggesting a correlation between deficiency of the posterior acetabular wall and the earlier onset of pain. Level of Evidence: Prognostic Level IV. See Instructions to Authors for a complete description of levels of evidence....

Although a wide variety of acetabular deformities in developmental dysplasia of the hip (DDH) have been reported, the morphologic features of the entire pelvis in DDH are not well characterized and their correlation with acetabular deformity is unknown. We determined whether there was a rotational deformity of the entire innominate bone, and if so, whether it related to acetabular version and coverage. We examined the morphologic features of the pelvis using CT for 50 patients with DDH (82 hips). Forty normal hips were used as controls. The innominate rotation angle was determined at three levels in the axial plane. The acetabular sector angle served as an indicator of acetabular coverage of the femoral head. We evaluated the association between innominate rotation angles and acetabular version and coverage. We observed greater internal rotation of the innominate bone in patients with DDH than in the control subjects. Internal rotation of the innominate bone was associated with increased acetabular anteversion angle and acetabular inclination angle. In hips with acetabular retroversion (nine of 82 hips; 11.0 %), the entire innominate bone was externally rotated, compared with hips with acetabular anteversion. Internal rotation of the innominate bone also was associated with decreased anterior and superior acetabular coverage. Our observations suggest structural abnormalities exist throughout the pelvis in DDH, and the morphologic abnormalities of the acetabulum are not caused solely by local dysplasia around the hip, but are influenced by the morphologic features of the entire pelvis. Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: The purpose of this study was to examine intraarticular pathology in patients younger than 20 years with symptomatic developmental dysplasia of the hip. Methods: We performed hip arthroscopy during corrective osteotomy in 23 hips in 22 patients. All patients were female, and the average age at operation was 16.4 years. Eighteen hips were in a prearthritic stage, and 5 hips were in an early stage. The presence and location of cartilage degeneration and labral tears were evaluated. Second-look arthroscopy was performed in 13 hips in 12 patients. Results: Fourteen hips (77.8%) in the prearthritic stage had cartilage degeneration. Cartilage lesions were more frequent in the acetabulum than in the femoral head (72.2% vs 16.7%). Sixty-one percent of acetabular lesions were located at the anterosuperior area. Labral tears were observed in 77.8% of hips in prearthritic stages located at the anterosuperior (72.2%) and superior (44.4%) areas. The degree of cartilage and labral lesions in the early stage was more severe than in the prearthritic stage. On second-look arthroscopy, there were no changes in the state of the cartilage and labrum in the majority (84.6%) of hips. Conclusions: The incidence of intraarticular lesions in developmental dysplasia of the hip was high, even in the prearthritic stage. These lesions tended to originate in the anterosuperior area of the acetabulum and were generally progressive. Level of evidence: Therapeutic study, level IV.