Developmental Dysplasia of the Hip
Developmental dysplasia (or dislocation) of the hip (DDH) is an abnormal development of the hip joint leading to a joint that is dislocated or prone to dislocation. The condition is found in babies or young children and affects 1-3% of newborns.
A dislocation is where the two bones that make up the joint are not lined up properly. The hip joint is made up of a ball at the top of the thighbone (called the femoral head) which sits inside the socket (called the acetabulum) of the pelvis. In DDH the femoral head slips and does not properly join the hip socket or acetabulum.
In hips affected by DDH, the ball is not stable within the socket because the socket is abnormally shallow. The ligaments around the hip joint that normally help hold the hip joint in place, are also abnormal, allowing the ball to slip out of the socket.
DDH can vary from mild forms where there is slightly less stability in the joint to severe where the joint easily dislocates. It may be present on one side only or it may affect both hips.