Hip dysplasia in babies is a condition where the hip joint doesn’t form properly, leaving the ball of the thighbone loosely fitting in its socket or, in more severe cases, partially or fully dislocated. It’s one of the most common skeletal conditions in newborns, affecting roughly 1 in 1,000 babies. The good news: when caught early, treatment is simple and highly effective, and most children go on to develop completely normal hips.
How the Hip Joint Develops
A baby’s hip is a ball-and-socket joint. The round top of the thighbone (the “ball”) sits inside a cup-shaped hollow in the pelvis (the “socket”). In a healthy hip, the socket is deep enough to hold the ball snugly in place while still allowing a wide range of movement. In a baby with hip dysplasia, the socket is too shallow. This means the ball can slip partially out of position (subluxation) or come out entirely (dislocation).
At birth, much of a baby’s hip is still made of soft cartilage rather than hard bone. This is actually an advantage: because the joint is still moldable, early treatment can guide it into the correct shape as the cartilage gradually hardens into bone over the first year of life. Left untreated, the socket may never deepen properly, leading to problems with walking, chronic pain, and early-onset arthritis.
What Causes It
There’s no single cause. Hip dysplasia results from a combination of genetic and environmental factors that affect how the joint develops in the womb and shortly after birth.
The biggest risk factor is family history. A baby with a parent or sibling who had hip dysplasia is significantly more likely to develop it. Being the firstborn also raises risk, likely because a first pregnancy stretches the uterus less, putting more pressure on the baby’s hips. Babies in the breech position (feet or bottom first) during the final weeks of pregnancy face roughly a 1 in 10 chance of some degree of hip instability, making breech positioning one of the strongest individual risk factors.
Girls are affected about four to five times more often than boys. Hormones that relax the mother’s ligaments near delivery may also loosen the baby’s joint, and female infants appear more sensitive to this effect. Low amniotic fluid and being a larger baby in a tight uterine space can also contribute by limiting fetal movement and keeping the hips in a less-than-ideal position.
How Doctors Check for It
Pediatricians screen for hip dysplasia as part of every newborn exam, usually within the first 48 hours of life and again at follow-up visits during the first year. The physical exam involves gently moving each hip through a specific range of motion, feeling for a “clunk” or shift that indicates the ball is sliding in or out of the socket. These clinical maneuvers can detect instability in the first few weeks, but they become less reliable as the baby grows and the joint tightens.
If anything feels abnormal, or if the baby has risk factors like breech positioning or a strong family history, the doctor will order an ultrasound. Ultrasound is the preferred imaging tool for babies under about four to six months because the hip is still mostly cartilage and won’t show up well on X-ray. After six months, once more bone has formed, X-rays become the standard way to evaluate the joint.
Some cases aren’t obvious at birth and only become apparent as the child grows. Signs that parents might notice include uneven skin folds on the thighs, one leg appearing shorter than the other, limited range of motion when changing a diaper (one hip doesn’t open as wide), or a limp once the child starts walking.
Severity Ranges Widely
Not all hip dysplasia is the same. At the mildest end, the hip is simply “loose” or slightly unstable but sits in the socket on its own. Many of these mild cases resolve without any treatment in the first few weeks of life as the ligaments tighten. Moderate dysplasia means the socket is noticeably shallow and the ball can be pushed partially out of place. Severe dysplasia involves a hip that is fully dislocated, with the ball sitting entirely outside the socket.
Most diagnosed cases fall on the milder end of the spectrum. Only a small fraction involve a fully dislocated hip at birth. The severity determines the treatment approach and timeline.
Treatment in the First Six Months
The standard first-line treatment for babies diagnosed before six months is a soft brace called the Pavlik harness. It holds the baby’s hips in a flexed, outward position (a “frog-leg” posture) that keeps the ball seated deeply in the socket. This positioning gives the socket the consistent contact it needs to remodel and deepen naturally.
Babies typically wear the harness full-time for six to twelve weeks, though exact timelines vary depending on severity and how quickly the hip responds. The harness fits over clothing, and parents can still feed, hold, and bathe the baby with some adjustments. It looks more restrictive than it feels for the baby. Most infants adapt quickly.
The Pavlik harness succeeds in roughly 85 to 95 percent of cases when started early. Follow-up ultrasounds track the hip’s progress, and once imaging confirms the socket has developed enough depth and stability, the harness is gradually weaned. Babies treated successfully in the first few months typically show no long-term effects and go on to walk at the normal age.
When Bracing Isn’t Enough
If the harness doesn’t achieve a stable hip, or if dysplasia is diagnosed after six months, treatment becomes more involved. The next step is a closed reduction, a procedure done under general anesthesia in which a doctor manually guides the ball back into the socket without surgery. Afterward, the baby wears a rigid body cast (called a spica cast) for several months to hold the hip in place while it heals and remodels.
A spica cast covers the torso and one or both legs. It’s waterproof in some versions but generally requires creative solutions for diaper changes and daily care. The casting period typically lasts about three months, sometimes with a cast change partway through as the baby grows.
In cases where the hip can’t be repositioned without surgery, an open reduction is performed. This involves a small incision to remove any tissue blocking the ball from seating properly, followed by casting. For older toddlers or children with more significant bony abnormalities, surgeons may reshape the socket or thighbone in a procedure called an osteotomy. Recovery from these surgeries generally involves several months in a cast followed by gradual return to normal activity.
Long-Term Outlook
Timing is the single biggest factor in outcomes. Babies diagnosed and treated in the first three months of life have an excellent prognosis, with the vast majority developing completely normal hips that cause no problems into adulthood. The later treatment begins, the more likely the child will need more invasive procedures and the higher the chance of some residual abnormality in the joint.
Even children who require surgery generally do very well. They walk, run, and play sports like their peers. The main long-term concern is a slightly elevated risk of hip arthritis in adulthood, particularly if the socket never fully remodeled to normal depth. Regular follow-up through childhood, sometimes into the teen years, helps ensure the hip continues developing properly during growth spurts.
What Parents Can Do
Beyond following the screening and treatment plan, the way you carry and swaddle your baby can support healthy hip development. When swaddling, keep the blanket loose around the hips and legs so the baby can bend and spread their knees freely. Tight swaddling that forces the legs straight and together pushes the ball against the shallow part of the socket and can worsen or even cause dysplasia in a vulnerable infant.
When using baby carriers, choose ones that support the thighs from knee to knee, allowing the hips to sit in a spread, flexed position rather than dangling straight down. The International Hip Dysplasia Institute endorses carriers that keep the baby’s knees at or above hip level with the thighs supported. Car seats and bouncer chairs that position the baby with hips bent and apart are generally fine and even beneficial.
If your baby has risk factors, particularly a breech birth or a first-degree relative with hip dysplasia, mention this to your pediatrician even if the physical exam seems normal. Requesting an ultrasound around six weeks of age can catch subtle cases that a physical exam alone might miss.