Parents of newborn infants have been asking me questions about how common hip instability and dislocations are in babies and how they can recognize this problem. Let me make sure everyone is hip to knowing about this problem and provide some information on the topic.
Hip instability, which can lead to dislocation, is a deformity of the hip that can happen before, during or weeks after birth. In most babies, the hip joint consists of what looks like a ball at the end of the long thigh bone of the leg, called the femur, which sits comfortably in a socket in the pelvic bone.
Sometimes the ball part of the femur moves back and forth and comes out of that socket, making the hip slightly unstable. If the femur slips out completely, then the hip is said to be dislocated.
What causes this problem? We aren’t sure but several factors may play a role, including a family history of others having this problem. Other factors include a baby being cramped in the uterus, born in a breech position, or swaddled too tightly. In some cases, a mother’s hormones during pregnancy can make the ligaments or bands holding the hip joint together relax enough to cause joint instability.
Since a hip dislocation is not painful, how can you tell if it has occurred in your baby? If there is asymmetry in the folds or creases seen in the groin or buttocks, or if, as your baby’s hips are examined by their health care professional, there is limited range of motion of one hip relative to another, then the hip may be dislocated. Also, if a clunk is heard in moving the hip back and forth during the exam, it may also signify instability or dislocation and a need to confirm the diagnosis with a hip-ultrasound imaging study.
If hip instability is detected, your child’s doctor will have a pediatric bone specialist check the hip out as well. Sometimes mild instability gets better by itself, but commonly infants will be placed in a type of pelvic harness for 6 to 12 weeks to keep the ball of the femur in the socket until the hip joint ligaments have become strong enough to keep it from slipping out. If the problem is not recognized for months after birth, the harness will no longer work and surgery may be indicated to prevent complications like different leg lengths or a limp when walking starts.
The good news is that, if treated early, developmental hip instability or dislocation results in your infant walking normally usually by a year or age with no delay in their motor skills.
Hopefully tips like this will stabilize your thinking when it comes to knowing more about what to do if you think your child’s hip is unstable or dislocated.
Lewis First, MD, is chief of Pediatrics at The University of Vermont Children’s Hospital and chair of the Department of Pediatrics at the Larner College of Medicine at UVM. You can also catch “First with Kids” weekly on WOKO 98.9FM and WPTZ Channel 5, or visit the First with Kids video archives at www.UVMHealth.org/MedCenterFirstWithKids.