Developmental Dysplasia of the Hip (DDH)

Description

Developmental dysplasia of the hip (DDH) describes a range of hip problems, present from around birth, in which the ball and socket of the hip do not fit together properly. It spans a spectrum — from a socket that is simply shallow or a hip that is loose, to a hip that partly slips out (subluxates) or is fully out of place (dislocates). Because it develops before and around birth, newborn checks are how it is most often caught.

How it happens (mechanism)

The hip is a ball-and-socket joint, and there is an important developmental rule: the socket only deepens properly if the ball sits snugly inside it during growth. In other words, the ball is the mold for the socket. In DDH, the ball is not well-seated, so the socket stays shallow and the hip stays loose or out of place — and because the socket molds to whatever position the ball is in, an unseated hip tends to become progressively more abnormal over time.

The risk factors all reflect a hip that was either crowded or loose before birth: breech position (hips held up and the legs extended), being firstborn (a tighter womb), being female (extra ligament looseness from maternal hormones), a family history of DDH, and tight swaddling with the legs held straight. The flip side of the molding rule is the hopeful part: if the hip is seated early, normal development can be “re-routed” back toward normal.

What matters

With DDH, timing is everything. Caught early in a newborn or young infant, a simple harness that holds the hip seated usually allows it to develop normally — and successfully treated early DDH has the best long-term outlook of the major childhood hip conditions. Missed until a child is walking, it requires bigger surgery and carries a higher chance of long-term problems such as early arthritis. That contrast is the whole reason for newborn hip exams and for screening ultrasounds in babies at higher risk. A simple preventive step is hip-healthy swaddling — keeping the hips able to bend and spread, rather than wrapping the legs tightly straight.

Symptoms and signs

DDH often causes nothing that a parent would notice, which is why screening matters. Possible clues include:

• Uneven skin folds of the thighs or buttocks
• A hip “clunk” felt by the doctor during the newborn exam
• Limited spreading (abduction) of one hip, or one leg that seems shorter
• In a child who is walking, a limp, a waddle, or walking up on the toes of one side

How it is diagnosed

Newborns are checked with specific physical-exam maneuvers (the Barlow and Ortolani tests). Before about 6 months of age — before the ball has turned from cartilage into bone — ultrasound is the best imaging test; after about 4 to 6 months, X-rays are used. Babies at higher risk (for example, breech position or a family history) are often screened with ultrasound even when the exam seems normal.

Treatment

Treatment depends heavily on age. In newborns and young infants, a Pavlik harness (or a similar brace) holds the hips bent and gently spread so the ball stays seated while the socket develops. If bracing does not succeed, or the child is older, the hip may be guided back into place under anesthesia and held in a cast (closed reduction with a spica cast). Older children may need an operation to place the hip and reshape the bone (open reduction and osteotomy). As a rule, the older the child at diagnosis, the bigger the treatment.

Recovery and long-term outlook

When DDH is found and treated early, the outlook is excellent and the hip usually develops normally. Diagnosis later in childhood means more involved treatment and a higher chance of residual shallowness or early arthritis. Children treated for DDH are followed over time to confirm the hip keeps developing well.

When to call the doctor

Raise any concern about a hip clunk or click, uneven leg or buttock creases, a leg that looks shorter, limited hip movement, or a limp or waddle once your child is walking. Infants at higher risk — breech babies and those with a family history — should be screened even if they appear normal.

Learn more

POSNA OrthoKids — Developmental Dysplasia of the Hip (DDH): orthokids.org

This information is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. For specific concerns about your child, consult a board-certified, fellowship-trained pediatric orthopaedic surgeon.