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Understanding adult DDH

Background information about Developmental Dysplasia of the Hips:

The hip Joint is a ball and socket joint composed of two main parts: the ball, which is the top of the main thigh bone (femur) and the socket, which is made up of the pelvic bones and called the acetabulum. To develop properly the ball must be in contact with the socket the whole time.  If one part is not in the right place the other cannot grow correctly.

Developmental dysplasia of the hips – or DDH – occurs when hip joints have not developed properly.  This can range from babies with unstable hips that dislocate, through to people with mild abnormalities of the socket that present later.  Most adults with hip problems due to DDH have known about it since they were younger and have undergone previous treatments.  However there are also those who do not develop any symptoms until well into adulthood.

DDH is more common in females – 80% of cases are girls.  You can have just one side affected or it can affect both (in 20% of cases).

Understanding adult DDH

In adults the diagnosis is usually made with a plain x-ray.

CT and MRI scans are also used to look at the soft tissues and for planning surgery.

But why have I got it?

Doctors use the term ‘idiopathic’ for DDH. This means they really don’t know for definite why some people have this condition and others don’t.  However they do know that there are some things that mean you might be more likely to have it.  The main ones are a breech presentation at birth, birthweight >5kg and a positive family history.  Conversely there are many people with DDH who have not been affected by any of the above.


There is a hereditary component to DDH.  There is a 12 fold increase in risk for 1st degree relatives. This means that if you have DDH, your children or siblings are 12 times more likely to have DDH than someone with normal hips.

Why do you get symptoms?

Quite simply, dysplastic hips are not as good at supporting the body as a normal hip and therefore can wear out over time.  You might ask why you have not always had pain.  This is because our bodies are very good at compensating, to a point.  Once this point is reached the hip can no longer compensate and symptoms appear.  In adults this usually happens between the age of 20 and 40.

Most people complain about an intermittent sharp pain in their groin that is worse with activity. Over time, however, this becomes more constant and can interfere with everyday activities such as walking.

Stiffness in the joint does not usually happen in the early stages.  Arthritis can develop as a result of this, usually much earlier than someone with normal hips, but this is a late problem.  Pain occurs when the edge of the socket is impinged on the neck of the thigh bone. This occurs when your leg is bent to your chest and you try to stick your ankle out (eg when putting on shoes, getting out the car, or scratching your toes with your knee bent).

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