The hip is where the thigh bone and pelvis meet. The thigh bone has a ball-shaped top. This ball fits into a cup shape area on the pelvis. Developmental dysplasia of the hip (DDH) is a problem with how these bones fit together. The exact problem can vary between children but may include:

  • Ball of the thigh is loose inside the cup of the pelvis—makes the hip unstable
  • Ball moves easily out of the cup—causing a dislocation of the hip
  • Ball and cup do not meet at all
  • The cup is improperly shaped

The Hip Joint
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The exact cause of DDH is not known. Some factors that may play a role include:

  • How the baby is positioned in the womb
  • Maternal hormones
  • Genetics

Certain carrying or wrapping techniques may also affect the growth of the hip, especially methods that have the child tightly bound in a position with the hips straight out and turned in.