What Is Hip Dysplasia?

Hip dysplasia, sometimes called DDH (developmental dysplasia of the hip), is a condition where the hip joint socket (acetabulum) is too shallow. The femoral head (ball) is partially uncovered and can sometimes be facing more backward than forward (retroversion). DDH can lead to early arthritis.

Some mild dysplasia problems may be treated arthroscopically, while others must be treated through a surgery called periacetabular osteotomy.

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What Causes Hip Dysplasia?

This condition happens during a child’s early development. DDH is also the most common hip deformity that causes symptoms (hip pain) in adults as well as the most common cause of osteoarthritis in the hip.

Individuals with acetabular dysplasia often go through childhood and adolescence without symptoms or knowledge of their condition. However, when they reach young adulthood, they may experience hip pain. At that time an X-ray will reveal the acetabular dysplasia.

Symptoms of Hip Dysplasia

Many people, especially women, have dysplasia and don’t know it until their mid to late twenties or thirties. These are the most common symptoms of DDH:

  • Pain in the front of the hip (groin) after sitting or walking, such as a dull ache
  • Difficulty walking up or downhill
  • Catching or popping of the hip joint

If left untreated, patients with DDH will need hip replacement (total hip arthroplasty) at some time in their life.

Classic Dysplasia vs. Retroversion

Classic dysplasia is demonstrated in figure A where the socket (acetabulum) is facing forward and the lines representing the front wall (anterior) of the socket and the back (posterior) wall of the socket are not overlapping. In classic dysplasia there is not enough coverage of the outside of the femoral head.

Retroversion, figure B, is when the opening of the socket is facing to the side or backwards causing the femur to contact the front of the socket when it rotates. This can cause femoroacetabular impingement and can damage the cartilage inside the socket (articular cartilage) and the rim of the socket (bone or labrum).

The arrow shows the part of the anatomy (ischial spine) that should not usually be visible unless this whole region of the pelvis is twisted backwards. There is often enough or too much lateral coverage of the head, but there may not be enough coverage of the back of the head.

Surgery for Hip Dysplasia: Osteotomy

You may want to consider surgery if you have a pain that is in the front groin (anterior) that affects daily activities and prevents you from doing the things you want to. Also if X-rays show dysplasia with early degenerative changes (mild arthritis), but still evidence of good cartilage, your doctor may recommend an osteotomy.

Hip dysplasia is not always painful, however. Sometimes people have dysplasia without painful enough symptoms to choose surgery. In those patients we monitor the hips over time with X-rays and re-evaluate their symptoms every year or two.