Developmental Dysplasia of the Hip

Definition

Developmental dysplasia of the hip (DDH) is a spectrum of abnormal development of the hip in which the femoral head and acetabulum have an abnormal relationship — ranging from a shallow dysplastic but located hip, through a subluxatable/dislocatable hip, to a frankly dislocated hip. Early detection is vital because timely treatment gives an excellent outcome, whereas late diagnosis leads to permanent deformity and early osteoarthritis.

Risk Factors

The classic associations (remembered as the ‘6 Fs’-type list) include a positive family history, female sex (much commoner in girls), firstborn, breech presentation, oligohydramnios, and other ‘packaging’ disorders (congenital torticollis, metatarsus adductus). The left hip is more often affected.

Neonatal screening manoeuvres: Barlow’s test dislocates an unstable hip; Ortolani’s test relocates a dislocated hip with a palpable ‘clunk’.

Clinical Features & Screening

In the neonate, screening uses Ortolani’s test (abduct and lift the flexed hip to relocate a dislocated head — a palpable clunk) and Barlow’s test (adduct and gently push to dislocate an unstable hip). In the older infant, signs are limited hip abduction, asymmetrical skin/thigh creases, apparent femoral shortening (Galeazzi/Allis sign) and, once walking, a painless limp or waddling (Trendelenburg) gait.

Investigations

Under 6 months the femoral head is unossified, so ultrasound is the investigation of choice (Graf technique assesses acetabular morphology and stability). After the head ossifies (around 4–6 months), a plain radiograph is used, assessing Shenton’s line, the acetabular index and the position of the head relative to Perkin’s and Hilgenreiner’s lines.

Management

Treatment depends on age. 0–6 months: a Pavlik harness holds the hips flexed and abducted to allow the acetabulum to develop and the hip to stabilise. 6–18 months (or Pavlik failure): closed reduction and hip spica under anaesthetic, sometimes with adductor tenotomy and arthrogram. Older / irreducible / late hips need open reduction, often combined with femoral and/or pelvic osteotomy to correct the bony deformity. The earlier the treatment, the better the result.

• Spectrum from dysplasia to dislocation; early diagnosis gives excellent outcomes.
• Risk: female, firstborn, breech, family history, oligohydramnios; left hip commonest.
• Ortolani relocates, Barlow dislocates; after 3 months → limited abduction is the key sign.
• Ultrasound <6 months, radiograph after ossification.
• Pavlik harness (0–6 mo) → closed reduction/spica → open reduction ± osteotomy; beware AVN.