A CT study to understand the shape of hips with developmental dysplasia

What is it about?

We looked at CT scans done of 117 patients with hip dysplasia, to understand the shape of the hip socket (acetabulum) and explain how it differed from a normal hip. We found that the dysplastic acetabuli were elongated, as if stretched out, from top to bottom, but had the same width as normal hips. They dysplastic ones were much less deep than normal. We did not find a significant change in orientation (version) of the main part of the acetabulum, but the upper (stretched out) area was retroverted (pointing more posteriorly).

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Why is it important?

Current procedures that redirect the dysplastic acetabulum can improve stress distribution across the hip joint, but cannot compensate for the overall shape abnormalities of the dysplastic acetabulum. Because the dysplastic acetabulum is shallower, and elongated, there will continue to be imperfect distribution of cartilage pressures in the hip joint. Therefore, there is more urgency to identify acetabular dysplasia earlier, and correct it while a child is still growing, and has the chance to remodel their acetabulum.