Developmental dysplasia of hip

Radiograhic features of DDH: shallow acetabulum acetabular angle greater than 30 degrees (same as alpha angle less than 60 degrees) small capital femoral epiphysis delayed ossification of the femoral head acetabular sclerosis loss of Shenton's curve femoral head lateral to Perkin's line femoral head superior to Hilgenreiner's line

Shenton's curve: smooth, curved line connecting medial border of femoral metaphysis with the superior border of the obturator foramen

Hilgenreiner's line: a horizontal line through the triradiate cartilage of the acetabulum

Perkin's line: a vertical line (perpendicular to Hilgenreiner's line) from the lateral margin of the ossified acetabular roof that is normally tangential to the lateral margin of the ossification center of the femoral head

Acetabular angle: angle that the acetabular line makes with Hilgenreiner's lin