Most people who have hip dysplasia (also referred to as congenital hip problems) are born with it, even though symptoms may not always develop until young adulthood. Hip dysplasia occurs when the hip socket doesn’t fully cover the ball of the thighbone (femur). The result is that the hip joint can become dislocated, either partially or fully, and begin to wear out.
Hip dysplasia runs in families and is more common in girls than boys. The condition may develop in the womb if the ball of the baby’s hip joint moves out of its proper position in the last month before birth, causing the socket to develop more shallowly than normal. If the space inside the womb is very limited, which is common with a large baby or breech presentation as well as in first pregnancies, hip dysplasia can be the result.
Congenital hip problems increase the risk of hip osteoarthritis in later life, as cartilage becomes worn away, preventing the bones from gliding smoothly against each other.
In young children with the condition, one leg may be noticeably longer than the other, or one hip may be less flexible. Once the person reaches teenage years or early adulthood, pain and instability may be experienced in the hip and the front of the groin. The pain may cause a limp and can also lead to discomfort in the back of the hip and side.
All babies are routinely checked for hip dysplasia by carrying out a physical examination of the hips and ensuring a full range of motion in the legs. In teenagers and adults, suspected hip dysplasia may be diagnosed using an X-ray, ultrasound or MRI to determine how well the ball and socket joints fit together and whether there is wear to the cartilage that lines the joint.
If the condition affects infants under six months old, a soft brace may be used to hold the ball part of the joint firmly into the socket for several months. This encourages the socket to mould correctly to the shape of the ball. For older babies, a full body cast might be needed.
In older children and adults, surgery may be recommended. Possible procedures include:
- Hip arthroscopy – this is a minimally invasive procedure that entails making a small incision in the skin and inserting a thin instrument called an arthroscope, which enables the consultant to see inside the joint and make repairs using tiny surgical instruments.
- Periacetebular osteotomy – this entails cutting the socket free from the pelvis and altering its position to match up more closely with the ball at the top of the femur.
- Hip replacement surgery – this may be necessary for older adults who have developed osteoarthritis as a result of hip dysplasia.