What is the role of plain radiography in the workup of developmental dysplasia of the hip (DDH)?

Updated: Feb 26, 2018
  • Author: Junichi Tamai, MD; Chief Editor: William L Jaffe, MD  more...
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Answer

Standard radiographic views for DDH include a standing anteroposterior (AP) view of the pelvis, with the hips in neutral position, and a false profile view in which the patient is standing angled at 65º from the x-ray plate. The radiograph is then taken, profiling the anterior aspect of the acetabulum. If any evidence of hip subluxation is present, an abducted internal rotation view can help determine if the hip reduces and better determines the true neck-shaft angle of the proximal femur.

Radiographic evaluation is typically carried out as follows (see the image below). From an AP radiograph of the hips, a horizontal line (Hilgenreiner line) is drawn between each triradiate cartilage. Next, lines perpendicular to the Hilgenreiner line are drawn through the superolateral edge of the acetabulum (Perkin lines), dividing the hip into four quadrants. The proximal medial femur should be in the lower medial quadrant, or the ossific nucleus of the femoral head, if present (usually observed in patients aged 4-7 months), should be in the lower medial quadrant.

Typical radiographic evaluation of developmental d Typical radiographic evaluation of developmental dysplasia of hip (DDH). From anteroposterior radiograph of hips, horizontal line (Hilgenreiner line) is drawn between each triradiate cartilage. Next, lines are drawn perpendicular to Hilgenreiner line through superolateral edge of acetabulum (Perkin line), dividing hip into 4 quadrants. Proximal medial femur should be in lower medial quadrant, or ossific nucleus of femoral head, if present (usually observed in patients aged 4-7 months), should be in lower medial quadrant. Acetabular index is angle between Hilgenreiner line and line drawn from triradiate cartilage to lateral edge of acetabulum. Typically, this angle decreases with age and should measure less than 20° by 2 years of age. Shenton line is drawn from medial aspect of femoral neck to inferior border of pubic rami. It should create smooth arc that is not disrupted. Disruption of Shenton line indicates presence of some degree of hip subluxation.

Additionally, the acetabular indices can be measured. These refer to the angle between the Hilgenreiner line and a line drawn from the triradiate cartilage to the lateral edge of the acetabulum. Typically, the angle decreases with age and should measure less than 20º by the time the child is aged 2 years. [44, 45]

The Shenton line — a line drawn from the medial aspect of the femoral neck to the inferior boarder of the pubic rami — can also be evaluated. This line should create a smooth arc that is not disrupted. Disruption of the Shenton line indicates the presence of some degree of hip subluxation.


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