Developmental Dysplasia of the Hip (DDH)
Developmental Dysplasia of the Hip (DDH) is an abnormal formation of the hip joint in which the ball on top of the thighbone (femur) is not held firmly in the socket. In some instances, the ligaments of the hip joint may be loose and stretched.
The degree of hip looseness, or instability, varies in DDH. In some children, the thighbone is simply loose in the socket at birth. In other children, the bone is completely out of the socket. In still other children, the looseness worsens as the child grows and becomes more active.
Causes Developmental Dysplasia of the Hip (DDH)
The cause is not clear. However, there are factors that are known to contribute to the chance of a baby being born with DDH. Only 1 in 75 babies with a risk factor has a dislocated hip. Risk factors include:
- Family history. If there is a parent, brother or sister with DDH, then this makes it five times more likely than normal for a child to have DDH.
- Gender. About 8 in 10 cases of DDH are female. This may be due to oestrogen (the female hormone) that is made by the female fetus (the unborn baby). This makes the ligaments stretchier and means that the bones are more likely to move out of position.
- Pregnancy conditions. If there is only a small amount of fluid in the uterus (womb) this is called oligohydramnios. This can increase the risk of developing DDH because the baby is not able to move about within the uterus as much.
- Breech position. If an unborn baby is in the breech position (feet down position in the uterus), this can put the legs in a position which increases the risk of DDH. Most breech babies are born by Caesarean section. These babies have a risk of DDH seven times higher than normal. (The risk of DDH for a breech baby delivered vaginally is 17 times higher than normal.)
- Firstborn baby. About 6 in 10 cases of DDH occur in firstborn children. This may be because the uterus is tighter and less elastic than future pregnancies so that the baby has less room to move.
- Other abnormalities. If the baby has cerebral palsy, spinal cord problems or other nerve and muscle disorders, this increases the risk of developing DDH. DDH is also more common in premature babies or babies born weighing more than 5 kg.
- Race. The risk of a child having DDH is much greater in certain races. For example, DDH is much more common in Native American children and much less common in Chinese and African American children. This may be due partly to the position that Native American babies are swaddled in.
Only between 1 in 7 and 1 in 4 babies (about 15-25%) with DDH are breech or have a family history of DDH.
Symptoms of Developmental Dysplasia of the Hip (DDH)
Some babies born with a dislocated hip will show no outward signs.
- Legs of different lengths
- Uneven skin folds on the thigh
- Less mobility or flexibility on one side
- Limping, toe walking, or a waddling, duck-like gait
How is Developmental Dysplasia of the Hip (DDH) diagnosed?
- Ultrasound. Gives a good picture of whether there is a problem with the hip joint or not. (An ultrasound scan is a painless test that uses sound waves to detect structures in the body. It is the same type of scan that is done routinely on pregnant women early in their pregnancy.)
- X-ray. Various measurements are taken on the X-ray picture of the pelvis and femur to determine whether a child has DDH.
Developmental Dysplasia of the Hip (DDH) Treatment
Developmental Dysplasia of the Hip (DDH) Treatment is needed because if the head of the femur is left in an abnormal position then the hip joint develops abnormally. The earlier treatment is started after birth, the greater the likely success of treatment and the lower rate of long-term complications.
Pavlik Harness. It is often the first treatment used in children under six months old. It usually needs to be worn for at least six weeks full-time and six weeks part-time in young babies. Older babies may need to wear it for longer.
- Surgery may be recommended for severe cases or older baby