Developmental Hip Dysplasia
Victoria (Australia) Government, Better Health Channel
Developmental Hip Dysplasia Explained
Developmental dysplasia of the hip (DDH), previously referred to as congenital dislocation of the hip (CDH), means that the hip joint of a newborn baby is dislocated or prone to dislocation. Around 95 per cent of babies born with DDH can be successfully treated. Approximately one in every 600 girls is affected, compared to just one in 3000 boys. The left hip is affected 3 times more often than the right hip. Dislocation of both hips is not uncommon. DDH is also more common in babies born with particular disorders, including cerebral palsy and spina bifida. There is a family history of DDH in one-third of cases.
Structure of the Hip Joint
The hip is a ball and socket joint. The femur (thigh bone) ends with a rounded projection, or ball, which fits into the hollowed out socket (acetabulum) of the pelvic girdle. The ball is anchored firmly into the socket with tough connective tissue called ligaments. In a baby with DDH, the socket is abnormally shallow, which prevents a stable fit. Slack ligaments may also allow the femur to slip out of joint.
The signs and symptoms of DDH include:
- Reduced joint mobility.
- A low clunking sound can be heard when the leg is gently rotated, which is the sound of the femur engaging the socket.
The stretch of skin between the anus and the genitals (perineum) is unusually wide. For unilateral dislocation symptoms include:
- The skin creases of the buttocks don’t match.
- One knee joint looks higher than the other.
The Causes Are Many
There are many causes of DDH, both genetic and environmental, including:
- Family history – around one-third of babies with DDH have a blood relative who also had the condition.
- Congenital disorders – DDH is more common in babies with disorders including cerebral palsy and spina bifida.
- Breech delivery – being born feet-first can put considerable stress on the baby’s hip joints.
- Multiple babies – crowding inside the womb may dislocate the hip.
- First time mother – the inexperienced uterus and vagina may cause a difficult or prolonged delivery.
Babies are routinely checked at birth to make sure their hip joints are properly positioned. The baby is laid on its back, and the doctor rotates each leg at the hip to ensure full joint mobility. A dislocated hip doesn’t have a full range of movement and tends to make a clicking or clunking sound as the ball of the femur moves in and out of the socket. An ultrasound is usually performed to confirm the diagnosis and help determine the extent of the dislocation. X rays, CT scans and magnetic resonance imaging (MRI) scans may also be used.
Treatment for Newborns
A baby born with a dislocated hip can be successfully treated with a Pavlik harness. This device holds the joint in place while the baby’s skeleton grows and matures. Subsequent x-rays will track the hip joint’s progress. The Pavlik harness is effective in over 85 per cent of cases. Most babies will require the harness for between six and 12 weeks and do not appear to be distressed by its use.
If a baby is diagnosed with a dislocated hip when they are six months old or more, then an anaesthetic will be required before the hip is manipulated into its proper position. An operation may also be needed. A hip cast applied after surgery helps to keep the hip joint in place, and subsequent x-rays will track the hip joint’s progress.
Sometimes, a child isn’t diagnosed with DDH until they are two or three years of age. Symptoms may include a distinct waddling gait, one hip lower than the other, a limp, and walking on tiptoe. Complications of untreated DDH in an older child may include stability problems with the knee joints and injury to nerves supplying the femur.
Long Term Outlook
Most babies born with successfully treated DDH don’t have any hip problems in later life. However, some may develop arthritis in the affected joint in their later years.
Where to Get Help
- Your doctor
- Maternal and child health nurse
Things to remember
- Developmental dysplasia of the hip, or DDH, means that the hip joint of a newborn baby is dislocated or prone to dislocation.
- DDH affects one in every 600 girls, and one in every 3000 boys.
- Treatment includes special harnesses, or operations and casts, depending on the age of the child at diagnosis.