Developmental Dysplasia of the Hip (DDH)

Developmental Dysplasia of the Hip (DDH) used to be called congenital dislocation of the hip. However, we now know that this condition is a developmental and ongoing process that is not always detectable at birth.

Dysplasia is the abnormal formation of the hip joint that occurs between fetal life and maturity as a result of instability. The ball at the top of the thighbone (femoral head) is not stable in the socket (acetabulum) and the ligaments of the hip may be loose or stretched. Clinically unstable hips are reported in 1/100 newborns with true dislocation (ball of hip outside socket) occurring in to 1/1000 newborns.

Maternal hormones that are associated with pelvic relaxation around the time of birth can aggravate the instability of a newborn hip joint by softening and stretching the baby’s hip ligaments. There is a 9:1 female predominance for DDH, which may in part be explained by the fact that the female babys’ own hormones may aggravate an abnormal looseness of the hip joint.

DDH is a multifactorial disease in which both environmental and genetic factors play roles. Causes may be physiologic, involving the child’s basic makeup, or mechanical, involving positional influences in the uterus. DDH does not result from injury or trauma.

Fetal development in the breach position may also be a cause of DDH. Of those children with DDH, 30-50% developed in a breach position though only 2-3% of babies born are delivered in a breach position, DDH is also associated with other disorders caused by intrauterine position, such as congenital muscular torticollus (wry neck), talipes equinovarus (club foot), metatarsus adductus (toes bent inward).

Children are asymptomatic at birth, which is why they are screened by physicians at the first exam and every well-baby visit that follows. The first sign of a problem is often a “clunk” or reduced range of motion when the child moves his/her hip joint. More subtle signs include a difference in the creases around the thigh or an apparent difference in the length of the legs. Parents often notice a waddle or limp when the child begins to walk. Older children experience pain and reduced range of motion of the hip.

If caught early, treatment of DDH simply involves maintaining the hip in a position of flexion (knee up toward head) and abduction (knee away from center line) for 1-2 months using a Pavlik harness. The Pavlik device maintains the proper position of the femoral head (ball of hip joint), allowing the ligaments to tighten and normal hip socket formation to occur. The Pavlik harness allows for motion as the child kicks his/her and children adapt to it easily. The harness has to be on the child 24 hours a day during the initial treatment period which can last weeks to months, depending on the results of ultrasounds. If DDH is picked up early and treated appropriately, 95% of children will have an excellent outcome with no hip; problems in the future.

In some children with DDH, especially older children, surgery is sometimes necessary to reshape and tighten the hip joint. So if there is a family history of hip problems, risk factors including breech delivery, or any differences in the appearance of the leg from one side to another, consult a specialist to make sure your child is OK.