Developmental Dysplasia of the Hip Risk Factors

Developmental dysplasia of the hip risk factors includes a variety of reasons, prenatal and postnatal, mechanical or hormonal risk factors.

DDH is an abnormal development or dislocation of the hip, secondary to capsular laxity and mechanical factors.

The older term congenital dislocation of the hip has gradually been replaced by developmental dysplasia, which was introduced during the 1980s to include infants who were normal at birth but in whom hip dysplasia or dislocation subsequently developed.

What are the Developmental Dysplasia of the Hip risk factors?

DDH risk factors include the following:

1. Breech positioning:

Prenatal positioning is strongly associated with DDH. The breech effect is most notable when the knees are extended, with an incidence of 20% seen for a single or frank breech.

2. female sex:

The newborn’s response to maternal relaxin hormones may explain the higher incidence of DDH among girls. These hormones, which produce the ligamentous laxity that is necessary for the expansion of the maternal pelvis, cross the placenta and induce laxity in the infant. This effect is much stronger in female than in male children.

3. Positive family history:

A family history of congenital dysplasia of the hip increases the likelihood of this condition to approximately 10%.

In Coleman’s study of Navajo families, hip dysplasia in one family member increased the risk for other family members fivefold. ^SRC

Newborns with DDH have also been found to have a higher ratio of collagen III to collagen I as compared with control subjects, which suggests a connective tissue abnormality in those with DDH.^SRC

4. Postnatal Positioning:

People who wrap their newborn babies in a hip extended position have a much higher incidence of DDH as compared with other populations.

The mechanism of action is believed to be the placement of the hips in full extension against the normal neonatal hip flexion contracture.

5. Racial Predilection:

Blacks and Asians have relatively low incidences of DDH (0.1 per 1000 to 5 per 1000), whereas whites and Native Americans have higher incidences (15 per 1000).

6. Firstborn child:

Less intrauterine space accounts for increased incidence of DDH in firstborn children.

7. Ligamentous laxity:

The influence of the maternal hormone, relaxin, that produces relaxation of the pelvis during delivery may cause enough ligamentous laxity in the child in utero and during the neonatal period to allow dislocation of the femoral head.

This theory has credibility because relaxin has been shown to cross the placenta, and DDH is more common in females who are presumably more susceptible to the influences of relaxin.