In order to reduce the risk of infant hip dysplasia, we recommend avoidance of swaddling with the hips and knees in an extended position. A leading proponent of swaddling, Harvey Karp, M.D., has stated, "Contemporary swaddling techniques...permit infants to be snugly wrapped with their hips being safely flexed and abducted." Additional free movement in the direction of hip flexion and abduction may have some benefit. The HALO SleepSack wearable blanket and SleepSack Swaddle have sufficient legroom to allow safe swaddling and free movement of the hips and knees.
Hip dysplasia is the medical term for instability, or looseness, of the hip joint that affects thousands of babies each year. This ranges from mild instability to complete dislocation. Approximately one out of every 20 full-term babies has some hip instability and two or three per thousand will require treatment.
Infant hip dysplasia is not a “birth defect” because nothing is missing. This looseness is because the mother makes hormones that help ligaments relax during the birth process. Those hormones affect the baby’s hips, and girls seem to be more affected than boys. The birth position may also stretch the hip joints and make them loose.
Fortunately, most loose hips in babies tighten up naturally and the hips grow correctly. That happens almost 90% of the time, but tight swaddling, genetics, and other conditions can prevent natural correction from occurring. There is also a recent understanding that mild hip dysplasia is a very common cause of hip arthritis in young adults. Almost one third of hip joint replacements before the age of 50 are because of unrecognized infant hip dysplasia. About 10% of all hip joint replacement surgery is because of minor forms of hip dysplasia.
A family history of hip dysplasia and breech position in the womb are the two biggest risk factors for infant hip dysplasia. About one in four babies in the breech position will have some hip dysplasia. About one in eight babies will have hip dysplasia if one parent has a history of hip dysplasia. The risk jumps up to one in three for future children when a mother and a child already have hip dysplasia. Girls are more likely to be affected than boys. These risks can add up, so a girl baby who is in the breech position with a family history of hip dysplasia is probably going to have infant hip dysplasia herself.
Other Risk Factors Include:
If your baby has one or more of these findings, make sure your doctor checks the hips during each check-up for the first six months of life. Also, you should read the information about prevention to see what you can do to protect your baby’s hips as much as possible.
Infant hip dysplasia and dislocation are usually diagnosed by routine examination of the hip joint. An ultrasound study of the hip may be recommended in a baby at risk or when the pediatrician has any concern about infant hip dysplasia. The ultrasound study is harmless and painless and gives the doctor a picture of the hip joint. The ultrasound study can also tell whether the joint is loose or not. The ultrasound study is rarely performed in the first two weeks of life because a lot of babies have loose hips that become stable after the mother’s relaxing hormones leave the baby’s body. The American Academy of Pediatrics recommends an ultrasound study at six weeks of age for almost all baby girls who were in the breech position. Other babies with risk factors may also benefit from an ultrasound, especially when the pediatrician has any concerns about the examination of the hips. An x-ray at four months of age or older is sometimes recommended after the bones are better formed.
Swaddling babies the wrong way can cause serious hip problems. It is important to leave the hips free to move and not tightly strapped with the legs straight out and together. Let the baby hold his or her hips bent up like they were when the baby was born and allow room for the legs to move freely.