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Acetabular retroversion is a condition where the hip socket (acetabulum) faces backwards (retroversion) rather than forwards.
Acetabular retroversion is a form of hip dysplasia (where the hip fails to form normally). There is no known cause for acetabular retroversion, however it may commonly exist with other hip problems such as FAI (femoroacetabular impingment), SCFE, and Perthes Disease.
Clinical features of Acetabular Retroversion
In many cases Acetabular Retroversion may be an incidental finding noticed on X-rays or scans without any problems at all. However, some patients may develop symptoms due to the femur (thighbone) abnormally hitting the pelvis, or instability from the femoral head slipping backwards out of the hip joint.
Common symptoms include:
- Hip Pain
- Hip Clicking/Catching
- Hip Giving way
In many cases Acetabular Retroversion may be missed on plain X-rays. It is recommended that Specialist Musculoskeletal Radiologists, or Specialist Hip Surgeons assess x-rays looking for Acetabular Retroversion. The signs on X-rays are often subtle and easily missed, and good quality X-rays are essential for the diagnosis.
Signs on X-ray include:
- Posterior Wall Sign
- Ischial Sign Sign
- Crossover Sign
CT Scans and MRI scans are very useful as they give a cross – sectional picture of the acetabulum and are the most accurate for looking at the bone and associated soft tissue structure of the hip joint.
Specific MRI and CT scans are useful for assessing the health of the hip cartilage, as well as the rotation of the entire leg which can contribute to the symptoms that patients with acetabular retroversion may experience.
Top: The normal appearance of the Acetabulum (Cup), showing the front (Red/anterior) and back (Yellow/posterior) walls. Bottom: Acetabular Retroversion where the front wall is more exposed than the back wall. Jamali et al 2007.