Hip dysplasia

Hip dysplasia is a condition where the ball (femoral head) and socket (acetabulum) of the hip joint don't form properly. The socket is usually too shallow and the ball isn't held tightly in place, so the hip joint is less stable. In severe cases, the ball can dislocate (pop out of its socket). In babies and infants, the misalignment is called developmental dysplasia of the hip (DDH). Most people with hip dysplasia are born with the condition. However, it can also develop in the first few months after birth. 

In some cases, people don't discover they have hip dysplasia until they are a teenager or adult as it can take a long time to make a definite diagnosis. Sometimes hip dysplasia symptoms are confused with those of another condition or DDH can be missed during the initial routine screening process of infants. Additionally, some types of hip dysplasia can develop in adolescence after a growth spurt.

What causes hip dysplasia?

The exact cause of hip dysplasia isn't known. It's thought the condition typically develops around the time of birth because at this point the hip joint is made of soft cartilage that is yet to harden into bone. If the ball isn't positioned firmly in the socket, the socket won’t form around it properly. This leaves it shallow. A shallow socket can also occur if the ball of the hip joint moves out of position when space in the womb becomes more limited in the weeks before birth.

There are some factors that are believed to increase the likelihood of a child developing the condition. These include:

• Family history: In some cases, there is a genetic link where a parent or other close relative has DDH
• First-born babies: First-born babies fit tightly in the womb, unlike subsequent babies
• Sex: Hip dysplasia is more common in girls. This may be due to anatomical differences in the female pelvis and the tendency of girls to have looser ligaments than boys
• Breech position: If the baby is in the breech position during pregnancy, there's a chance this can impact the way their hips develop.  

Your baby's hips are checked as part of a routine newborn physical examination. Their hip joints are moved gently to check for any problems. This isn’t painful for your baby. Here, the doctor, midwife or nurse is listening for any popping or clicking sounds and assessing how well the hip joint moves.

It’s routine for this examination to be performed again when they are six to eight weeks old. If the hip feels unstable during the initial check or at the six-week check, or there is a history of hip problems in the family, your consultant may recommend imaging tests such as an ultrasound scan, X-ray or MRI scan.

Hip dysplasia in adults

Most hip dysplasia cases are diagnosed at birth or within a few months. However, there are cases where symptoms don't occur until the baby becomes a teenager, so these can be difficult to diagnose. There are also instances where young adults have experienced symptoms since childhood without receiving a diagnosis. 

An X-ray can be used to detect hip dysplasia in an adult. Your consultant may request further MRI imaging to check for other conditions, such as a hip labral tear. You can get an appointment with one of our hip specialists for the next working day and, if necessary, have any imaging on the same day.

Whether you've been diagnosed as an adult or it's been confirmed that your child has the condition, there are ways to treat hip dysplasia. For your child, this may include:

Pavlik harness

The Pavlik harness is a fabric splint that secures the hips in a stable position and strengthens the ligaments around the joints. The harness promotes natural movement and should be worn constantly for one to two months. The orthopaedic team can make any adjustments needed to it during that time. You will be advised when the brace can start to be phased out and eventually be permanently removed. 

Surgery 

If the harness doesn't work or your child is diagnosed at a later date, your consultant may recommend surgery. The procedure could be closed reduction or open reduction. Both involve placing the ball of the hip joint back into the hip socket.

Closed reduction

This is a common procedure carried out on babies aged six to 24 months. It takes place after an arthrogram, which is where a dye is inserted into your baby's hip joint to produce detailed X-ray images. The closed reduction procedure takes place under general anaesthetic and the surgeon will make a small opening in the groin.

They will then surgically release the tendon in this area, which is known as the adductor tendon. This tendon is the band of tissue that runs between the pelvis and the knee and connects muscle to the bones. Its role is to stabilise the hips and help to move the legs together. The adductor is usually very tight, so the surgeon surgically cuts the tendon to release it. This is known as an adductor tenotomy and it relieves the pressure on soft surfaces of the hip and helps to keep the ball in the socket once the procedure is complete. The tendon heals quickly afterwards. Once the tendon is relaxed, the surgeon will gently move the ball at the top of your baby's thigh bone (the femoral head) back into its socket (the acetabulum).

Open reduction

Open reduction surgery to treat developmental dysplasia of the hip (DDH) in children is usually carried out if closed reduction hasn't worked. As with closed reduction surgery, the surgeon begins the procedure by releasing the adductor tendon. They then make an incision at the front of the hip so they can access the hip joint. They’ll clear out the tissue that might be causing the blockage between the ball and the socket.  

The surgeon manipulates the ball into the socket and the surrounding muscles are then repaired using sterile dissolving stitches. By repairing and tightening the muscles, this increases the likelihood of the hip joint remaining in place. 

Spica cast

After both open and closed reduction surgery, your child will be placed into a special hip cast known as a spica cast. This usually goes from the upper chest and runs down the hips and leg, finishing at the ankle. It keeps the joint in place, allowing it to strengthen, as well as stabilising the affected area. The constant contact between the ball and socket encourages the socket to grow into the correct shape. The cast is changed every six weeks and may need to be worn for up to six months. 

You or your child will be seen at our outpatient clinic for a follow-up appointment six to eight weeks after surgery. Our orthopaedic team will remove the spica cast and take an X-ray to make sure the cast is working and the hip is healing as expected. Your doctor will confirm whether the cast needs to be worn for longer at this point. 

Once the cast is removed, it can take a few days for your child to walk at their own pace. However, it’s common for this to take a week or two. Physiotherapy may be needed too, but your doctor will provide you with advice about this. 

Hip dysplasia treatments for adults

If you're an adult who's been diagnosed with hip dysplasia, any treatment or need for surgery will be based on the severity of your condition. Should surgery not be necessary, your consultant may suggest non-steroidal anti-inflammatory drugs for pain relief and lifestyle changes such as weight management and gentle exercise.

If the pain persists, your consultant may recommend that you undergo either a periacetabular osteotomy (PAO) or a total hip replacement (THR). Ignoring the pain will cause further degeneration of the joint and could reduce the possibility of corrective surgery in the future, so speak to a medical professional as soon as you can. 

A PAO involves repositioning the hip socket and screwing it in place to restore and maintain normal function. A THR means removing your damaged hip joint and replacing it with an artificial one, known as a prosthesis. Your consultant will recommend the most effective procedure for you.