The hip is a “ball-and-socket” joint. In a normal hip, the ball at the upper end of the thighbone (femur) fits firmly into the socket, which is part of the large pelvis bone. In babies and children with developmental dysplasia (dislocation) of the hip (DDH), the hip joint has not formed normally. The ball is loose in the socket and may be easy to dislocate.
Although DDH is most often present at birth, it may also develop during a child’s first year of life. Recent research shows that babies whose legs are swaddled tightly with the hips and knees straight are at a notably higher risk for developing DDH after birth. As swaddling becomes increasingly popular, it is important for parents to learn how to swaddle their infants safely, and to understand that when done improperly, swaddling may lead to problems like DDH.
In all cases of DDH, the socket (acetabulum) is shallow, meaning that the ball of the thighbone (femur) cannot firmly fit into the socket. Sometimes, the ligaments that help to hold the joint in place are stretched. The degree of hip looseness, or instability, varies among children with DDH.
In the United States, approximately 1 to 2 babies per 1,000 are born with DDH. Pediatricians screen for DDH at a newborn’s first examination and at every well-baby checkup thereafter.
DDH tends to run in families. It can be present in either hip and in any individual. It usually affects the left hip and is predominant in:
Some babies born with a dislocated hip will show no outward signs.
Contact your pediatrician if your baby has:
In addition to visual clues, your doctor will perform a careful physical examination to check for DDH, such as listening and feeling for “clunks” as the hip is put in different positions. Your doctor will use specific maneuvers to determine if the hip can be dislocated and/or put back into proper position.
Newborns identified as at higher risk for DDH are often tested using ultrasound, which can create images of the hip bones. For older infants and children, x-rays of the hip may be taken to provide detailed pictures of the hip joint