Erect Weight‐Bearing Pelvic Radiographs are Superior to Supine Radiographs for Diagnosis of Mixed Type Acetabular Retroversion Plus Developmental Dysplasia Hip Deformity

AR was observed in 31% of DDH cases and was associated with a notable posterior pelvic tilt during postural transitions. This tilt appeared to be a compensatory mechanism affecting the AR diagnosis. Key changes in the acetabular coverage, including increased anterior coverage and decreased superior posterior coverage, were also observed. Additionally, external rotation of the hemipelvis in mixed-type cases correlated strongly with the extent of AR and anterior acetabular coverage, suggesting that it may be a key contributor to the underlying mechanism of this mixed-type deformity.