Developmental dysplasia of the hip (DDH) is a long phrase pediatricians use to talk about babies whose hips aren’t where they’re supposed to be (dislocated).  We call it developmental because babies can be born with hips in the right place (the ball of the leg bone in the socket of the pelvis), then develop a dislocation.     

What makes this happen?

There are several factors that make a baby more likely to have a dislocated hip.  First, fetal and baby bones are soft so it’s easier for the ball to come out of the socket.  Second, hormones from mom make the baby’s ligaments more loose, especially in girls.  Third, the baby’s position in the womb can make them more likely to have a dislocated hip.  

After birth, how the baby is held or swaddled can affect their hips.  It’s not recommended to swaddle them tightly at the hips, as this can make them more likely to dislocate.  Holding them on your hip with their legs apart is a much safer position for the hips.     

Who is more likely to get this? 

Girls are more likely to have dislocated hips, possibly because they are more sensitive to the ligament stretching hormones from mom.  Babies in the breech position are more at risk, as are first born babies.  Conditions that decrease the room in the uterus can increase the risk, such as not enough amniotic fluid, or babies with certain deformities.  Also, having a family history of DDH increases the chance of having a baby with it.

How is DDH diagnosed?

From the first exam after birth to the one year exam, the baby’s hips are checked for stability with two specific techniques.  If a dislocation is found, or a significant instability noted, your pediatrician will order an ultrasound in the first few months or an xray after about 4 months old.  There is a difference in testing because baby’s bones still have more cartilage in them as a young infant, so an ultrasound shows them better.  

Other signs of DDH can be unequal leg lengths, limping when they start walking, or there can be no signs.

Once the diagnosis is made, your pediatrician will refer your baby to a pediatric orthopedist – a doctor who deals with bones and joints – for treatment.  

Can DDH be prevented?

Yes and no.  Holding and swaddling babies in ways that promote healthy hips can decrease or prevent some dislocations.  However, most of the risk factors can’t be changed, such as gender, birth order, and position in the womb.  In these cases, proper screening and quick treatment can provide the best outcome.   

How is DDH treated?

In general, the earlier DDH is discovered the better.  Most babies with DDH do well with the Pavlik harness when started in the first few months.  The pavlik is a soft harness that keeps the baby’s hips in the right place to allow for healing, but still lets the baby move.  Progress is monitored by the orthopedist and harness adjustments are made as the baby completes the several week treatment.  If the soft harness doesn’t work, or if the baby is older, then a more firm harness or a cast that covers the pelvis and both legs are used (spica cast).  If the harnesses don’t work, or in the cases when DDH is discovered after 2 years old surgery is required.

Unsuccessful treatment can lead to abnormal hip function, pain, and osteoarthritis.  

Bottom line.

Developmental dysplasia of the hip, or dislocation of the hip, usually is discovered at birth, but not always.  Treatment works better if it’s started as early as possible.  

Links.

International hip dysplasia institute.