Developmental Dysplasia of the Hip (DDH) in Babies: Screening, Ultrasound and Treatment

The hip joint consists of the ball at the upper end of the femur (femoral head) and the socket in the pelvis (acetabulum). In babies, the socket is still soft and largely cartilaginous; the ball must stimulate it correctly for it to deepen. Developmental dysplasia of the hip (DDH) disrupts this relationship: the socket remains shallow and the ball slips partly or completely out.

It is commonly called "congenital hip dislocation", but doctors use "developmental" because it is not always present at birth and may appear or worsen in the first months. One newborn examination is therefore insufficient; repeated early checks matter.

DDH is a spectrum rather than a single condition: a shallow socket (dysplasia), partial displacement of the ball (subluxation) or complete dislocation. Position within this spectrum affects both treatment and follow-up duration.

Most babies with developmental dysplasia of the hip (DDH) have no signs that families can recognise. They do not cry or become unsettled and move their legs normally. Its painless nature makes early screening essential. Nevertheless, the following signs warrant prompt orthopaedic assessment:

• One leg is difficult to open outwards during nappy changing
• Marked asymmetry between the skin folds of the legs and hips
• One knee sitting lower than the other when the baby lies on their back with knees bent, suggesting unequal leg lengths
• A snapping or clicking sensation heard or felt when moving the leg
• Waddling, limping or one-sided toe walking in a child beginning to walk
• A pronounced lower-back curve and legs held apart in bilateral cases

DDH can affect any baby, but certain factors substantially increase frequency. Even without symptoms, hip ultrasound is planned if any of the following applies:

• Breech presentation at birth
• A family history of hip dislocation (mother, father, sibling)
• Being female and firstborn
• Low amniotic fluid (oligohydramnios) and multiple pregnancy
• Associated congenital foot deformities or a twisted neck (torticollis)
• Tight swaddling that keeps the legs together and straight

Examination is the first diagnostic step. In newborns, specific manoeuvres (Ortolani and Barlow tests) assess whether the hip dislocates; in later months, hip abduction and leg length difference are evaluated.

Age determines the imaging method. In the first months, much of the infant hip is cartilage and is not clearly visible on X-ray, so hip ultrasound is used. Ultrasound is generally useful after the first weeks of life, commonly from weeks 4–6 until month 6. After approximately 4–6 months, as ossification progresses, assessment uses an anteroposterior hip X-ray.

The timing and number of repeat ultrasound scans depend on the baby's examination and risk factors. Following assessment at AC CLINIC in Ordu, suitable hip imaging is arranged; bringing any previous ultrasound or X-ray images is useful for comparison.

Treatment has one aim: place the femoral head in the socket and keep it there so the socket can develop normally. The method depends on the baby's age, whether the hip is dislocated or merely shallow, and previous treatment. Generally, the earlier the diagnosis, the simpler the treatment.

DDH treatment does not end when a harness or cast is removed. Socket development continues during growth, so children are reviewed periodically, usually until skeletal maturity. Walking, leg length and socket development on X-rays are monitored.

Rare treatment complications include impaired blood supply to the femoral head (avascular necrosis); follow-up also aims to detect these early. An underdeveloped socket may cause hip pain and early osteoarthritis in adulthood; this relationship is discussed on the hip osteoarthritis page.

Tight swaddling that holds the baby's legs straight and together is unsuitable for hip development. Families wishing to swaddle should use a loose technique that wraps the arms but allows the hips to bend and the legs to open sideways.

When holding a baby or using a carrier, a position with the legs apart and knees above hip level, similar to a 'frog' position, is hip-friendly. Separate guidance is provided for bathing, dressing and car seats while using a harness or cast; each point is explained at follow-up. Writing down questions and bringing them to appointments helps the process.