Noticing that one thigh has deeper skin folds or that the legs look different in length during a diaper change can raise worries about the hips. This article covers risk factors for developmental dysplasia of the hip (DDH), when babies are checked, and when to call.
Why It Happens
In DDH, the ball at the top of the thigh bone does not sit securely in the hip socket of the pelvis. The AAP clinical report states its aim as preventing or detecting a dislocated hip by 6 to 12 months of age. The most important risk factors are breech position at birth, a family history in a parent or sibling, and female sex. Low amniotic fluid and certain musculoskeletal conditions may also raise risk. The 2016 report newly named tight swaddling, with the legs held straight and together, as a risk factor.
How It Differs by Age
In newborns and up to about three months, the Ortolani and Barlow maneuvers by a clinician are central for checking whether a hip is dislocated or loose. If a newborn’s exam is equivocal, it can be repeated in about two weeks, and findings that stay equivocal beyond six weeks call for an evaluation by an orthopedic specialist. From around eight weeks, a hip that does not spread out as far as the other becomes an important clue. Uneven thigh folds are a common screening item, but few studies have tested how meaningful the sign is and folds differ in many healthy babies, so it is not used alone to diagnose.
The AAP advises against ultrasound for every baby. For infants with risk factors and a normal exam, imaging may be considered between six weeks and six months of age; for babies older than four months, X-ray can be an option.
Care at Home
During diaper changes, compare both thigh folds, buttock folds, knee heights, and how far each leg spreads, using the same position each time. Photos can help at the visit. Holding or carrying your baby with legs spread in a natural “M” shape is gentle on the hips. When swaddling, leave room for the hips and knees to bend and spread, and avoid wrapping the legs straight and tight. Do not pull a baby’s legs straight with force, and ask your clinician whether the hips are examined at well-baby visits. When DDH is found early, treatment is often relatively simple, such as a soft brace.
Common Misunderstandings
First, that uneven thigh folds always mean hip dysplasia; folds can differ in healthy babies. Second, that matching folds guarantee normal hips; if both hips are affected, folds can look symmetric. Third, that a baby with a problem hip will show pain; many babies have none. Fourth, that one normal exam settles it; the AAP notes no screening program eliminates late-appearing dislocation, so keep watching leg movement at later visits.
Signs That Need Emergency Care Right Away
Seek emergency care right away if your baby has a fever and barely moves one leg, cries hard when the hip is touched or moved, has a red, swollen hip area, or stops using a leg after a fall. If it is not an emergency but the legs look different in length, one leg spreads less, thigh folds stay uneven, a toddler limps after starting to walk, or there are risk factors such as breech birth or family history, contact your pediatrician. Consider talking with a pediatrician if you are unsure. This information reflects general guidance for the United States; if you live elsewhere, check with a local pediatrician. This information isn’t a diagnostic tool and doesn’t replace advice from a medical professional.