Developmental Dysplasia of the Hip (DDH): What It Is, How It's Found, and What Happens

Developmental dysplasia of the hip (DDH) is a condition in which the hip joint does not form correctly. The ball of the joint (the head of the femur) may sit in an abnormal position in the socket (acetabulum), may be loose and unstable, or — in severe cases — may be dislocated entirely. The term "developmental" reflects the fact that the condition may be present at birth or may develop in the weeks and months after birth.

DDH affects approximately 1–2 babies per 1,000 births in the UK, with milder instability occurring in a broader range of babies. When identified early, it is highly treatable with excellent long-term outcomes. Late diagnosis, by contrast, may require more complex surgery and is associated with a higher risk of arthritis in adulthood.

What Causes DDH

DDH is not caused by anything parents do or do not do. It results from a combination of genetic factors, intrauterine positioning, and ligamentous laxity.

Risk factors

Certain factors significantly increase the likelihood of DDH:

• Breech presentation — being in the breech position (bottom or feet first) late in pregnancy or at delivery is the most significant risk factor. Babies born breech have a risk of DDH around six times higher than those born head-down.
• Family history — a first-degree relative with DDH increases risk significantly
• Being female — DDH is four to five times more common in girls, possibly due to greater sensitivity to maternal relaxin (a hormone that loosens ligaments in preparation for birth)
• First-born child — the first pregnancy typically involves a tighter uterus and less space for movement
• Oligohydramnios — reduced amniotic fluid restricts fetal movement

Having none of these risk factors does not guarantee a normal hip. Conversely, having multiple risk factors does not mean your baby has DDH — the majority of high-risk babies have normal hips.

How DDH Is Detected

The UK has a two-stage screening programme for DDH.

Physical examination at birth

All babies are examined by a midwife or doctor within 72 hours of birth as part of the newborn physical examination. The hip examination includes two specific manoeuvres:

• Barlow's test — the examiner attempts to dislocate a femoral head that is in the socket, by gentle pressure in a specific direction
• Ortolani's test — the examiner attempts to relocate a femoral head that has slipped out of the socket, by gentle abduction of the hip

Abnormal findings include a palpable click or clunk, or a hip that clearly dislocates and relocates. A soft, high-pitched click (as opposed to a low, felt "clunk") is usually ligamentous and not significant.

Six-week examination

The hips are checked again at the six-to-eight week GP developmental check. Any concerns identified at this stage also prompt referral.

Ultrasound screening

Not all babies receive a hip ultrasound — it is reserved for those at higher risk or with clinical concerns. The NHS recommends ultrasound at six weeks (or earlier if the baby is to be discharged before this age) for babies with:

• Breech presentation at or after 36 weeks, including planned and emergency caesarean sections
• A first-degree family history of hip problems in childhood
• An abnormal or uncertain physical examination

Ultrasound is a highly effective way to evaluate the bony and cartilaginous anatomy of the hip and assess dynamic stability. It is safe, painless, and does not involve radiation.

Treatment

The approach to treatment depends on the severity of the DDH and the age at diagnosis.

Pavlik harness

For most babies diagnosed in the first six months of life, the Pavlik harness is the first-line treatment. It is a soft fabric harness that holds the baby's hips in a flexed, abducted position (knees up and out), which encourages the femoral head to seat correctly in the socket and allows the joint to develop normally.

The harness is worn full-time — 24 hours a day initially — and is adjusted at regular clinic appointments. The duration of treatment varies from a few weeks to several months depending on the severity and response to treatment. Most families adapt to the harness relatively quickly, though nappy changes and dressing require some adjustment.

Success rates with the Pavlik harness when used correctly in suitable babies are between 80 and 95 per cent.

Other treatments

If the Pavlik harness is unsuitable or unsuccessful, other options include:

• A rigid abduction brace (for babies over six months)
• Closed reduction under general anaesthetic, followed by a plaster cast (a hip spica) worn for several months
• Open surgical reduction in cases where the joint cannot be repositioned non-surgically

The more complex treatments are typically required in cases of late diagnosis — after the baby has begun weight-bearing — or in severe dislocations that do not respond to harness treatment.

Outcomes

DDH detected and treated in the first few weeks of life has excellent outcomes. The vast majority of babies treated with a Pavlik harness go on to have entirely normal hip development and full function with no lasting consequences.

Late-diagnosed DDH (after 18–24 months of age) often requires open surgery and the long-term outcomes, while generally good, are less predictable. There is an increased risk of avascular necrosis of the femoral head (damage to the blood supply of the ball joint) and a higher rate of osteoarthritis in middle age.

What Parents Should Know

If your baby is referred for a hip ultrasound, this does not mean they have DDH — it means they are in a higher-risk group and ultrasound will give a definitive answer. Most ultrasounds come back normal.

If your baby is fitted with a Pavlik harness, follow the clinic's instructions carefully regarding harness position, skin checks, and appointments. Do not remove or adjust the harness without instruction. Attend all follow-up appointments, as close monitoring is essential to ensure the hip is responding to treatment.

Ask your GP or paediatric orthopaedic team as many questions as you need to. DDH is a well-understood condition with established treatment pathways, and the team looking after your baby will have extensive experience.