Developmental Dysplasia of the Hip:
Screening the Newborn Hip

What developmental dysplasia of the hip actually is

Developmental dysplasia of the hip (DDH) is a term covering a spectrum of ways the infant hip joint can fail to develop normally — from a socket (acetabulum) that is slightly shallow, to a hip that is loose and can be pushed in and out of the socket, to a hip that is fully dislocated at birth. In a normally developing hip, the ball-shaped head of the femur sits snugly within the acetabulum, and the two grow and shape each other through infancy. If the femoral head is not well-seated early on, the socket doesn't form properly around it, and the problem tends to compound over time rather than resolve on its own.

DDH is common enough that essentially every newborn is examined for it. Estimates vary widely depending on how strictly the condition is defined: a frankly dislocated hip at birth affects roughly 1 in 1,000 infants, but when milder forms of instability and shallow-socket dysplasia are included, reported rates in screened populations range from about 1% to 7% of newborns. The wide range reflects a real clinical reality — many mild cases identified on a newborn exam or ultrasound stabilise on their own within the first few weeks of life without any treatment at all, which is one reason DDH surveillance is thought of as an ongoing process through the first year rather than a single pass/fail test at birth.

Who is at higher risk

DDH can occur in infants with no identifiable risk factors, but several factors are consistently associated with meaningfully higher risk, and most newborn screening protocols use them to decide which infants need closer follow-up or an ultrasound in addition to the routine physical exam.

How the diagnosis is made

Screening for DDH happens in stages over the first months of life. At birth and at subsequent well-baby checks, a physician performs specific manoeuvres — the Ortolani and Barlow tests — that check whether the hip can be felt to dislocate or relocate with gentle manipulation, along with a general look for asymmetric thigh or buttock skin folds, uneven leg length, or restricted hip abduction on one side. These tests are most reliable in the first few weeks of life and become less sensitive as an infant grows and the surrounding muscles tighten, which is exactly why repeated checks at multiple well-baby visits — rather than a single newborn exam — are the standard approach.

When the physical exam is abnormal, or when recognised risk factors are present even with a normal exam, hip ultrasound is the next step. Ultrasound is preferred over X-ray in the first four to six months because an infant's hip is still largely cartilage and doesn't show up well on plain film — the femoral head's bony nucleus typically isn't visible on X-ray until around four to six months of age. Ultrasound instead images the cartilage directly and is most commonly interpreted using the Graf method, which measures specific angles to classify the hip from normal (type I) through progressively more dysplastic and unstable grades (types IIa–IV, with type IV representing a fully dislocated hip). After about six months, once the ossific nucleus has appeared, plain radiographs become the more practical imaging tool.

One area of ongoing debate is whether every newborn should receive a screening ultrasound (universal screening) or whether ultrasound should be reserved for infants with an abnormal exam or a recognised risk factor (selective screening) — most countries, including Japan, use a selective or exam-based approach rather than universal ultrasound for every infant.

What the evidence says about treatment

The right treatment for DDH depends heavily on the infant's age at diagnosis and the severity of the dysplasia. For very mild, stable dysplasia identified on ultrasound in a young infant, many specialists recommend a period of watchful monitoring with repeat ultrasound, since a meaningful proportion of these hips normalise without any bracing at all. For hips that are unstable, subluxed, or dislocated, active treatment is generally recommended, and the mainstay of treatment for infants under six months is bracing.

The single most consistent finding across the treatment literature is that timing matters enormously — both for how likely treatment is to succeed and for the risk of complications, particularly avascular necrosis of the femoral head, a serious complication in which the blood supply to the developing femoral head is disrupted.

Age at treatment start	Typical approach	What the evidence shows
Under 3 months	Pavlik harness or similar brace	~89% success; low complication rates (AVN ~1%)
3–6 months	Pavlik harness or Tübingen splint, more intensive follow-up	Similar success rate, but notably higher AVN and residual dysplasia risk
6 months–2 years	Closed reduction and spica casting	Bracing alone less effective; casting often required
Over ~18–24 months	Open reduction ± osteotomy	Surgical correction typically needed at this stage

This is the central reason newborn hip screening exists in the first place: a hip that would need only a few months in a harness if caught early can require major reconstructive surgery if the diagnosis is missed until a child is walking with a limp. It's also why parents are sometimes surprised that a "mild" ultrasound finding is followed by fairly close monitoring rather than either immediate bracing or complete reassurance — in DDH, the trajectory over the following weeks often matters as much as the finding on any single scan.

When to see a specialist

Routine hip checks at newborn and well-baby visits are the main way DDH is caught, and parents don't generally need to seek out additional evaluation on their own for a child with a normal exam and no risk factors. However, prompt evaluation by a pediatric orthopaedic specialist is warranted for any infant with an abnormal newborn hip exam, a "click" or "clunk" felt during a hip exam, visibly asymmetric thigh folds or leg length, restricted movement of one hip, or any of the recognised risk factors above — especially breech presentation or a family history of DDH — even if the initial exam appears reassuring. For toddlers, a limp, asymmetric gait, or one leg that appears shorter than the other should also prompt evaluation, since DDH can occasionally be missed in early infancy and first become apparent once a child begins walking.