Developmental Dysplasia of the Hip

Courtesy: Dr Amr Abdelgawad, University of Texas,USA

Definition

Developmental dysplasia of the hip (DDH) encompasses a spectrum of abnormalities ranging from:

• Acetabular dysplasia

• Hip subluxation

• Complete dislocation of the femoral head

These abnormalities may be present at birth or develop during infancy.

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Epidemiology

• Incidence: 1–2 per 1,000 live births

• True dislocation: approximately 1 per 1,000 infants

• Left hip is more commonly affected

• May be associated with other conditions related to restricted intrauterine space, such as:

  • Metatarsus adductus

  • Torticollis

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Risk Factors

• Female sex

• First-born child

• Breech presentation

• Positive family history of DDH

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Clinical Examination in Newborns

Barlow Test

• Assesses whether the hip is subluxable

• Hip is flexed and adducted with posterior pressure

• A positive test indicates an unstable hip

Ortolani Test

• Assesses whether the hip is dislocated but reducible

• Gentle abduction with anterior lifting force

• A palpable or audible “clunk” indicates reduction of the femoral head into the acetabulum

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Ultrasound Evaluation

• Performed with the hip and knee flexed

• Transducer placed over the greater trochanter

• Based on Graf method

Key Angles

• Alpha angle

  • Assesses bony acetabular coverage

  • Larger angle = better coverage

• Beta angle

  • Reflects cartilaginous roof

  • Larger angle = increased risk of subluxation

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American Academy of Pediatrics (AAP) Recommendations for DDH Screening

Universal Screening

• All newborns should undergo physical examination

• Routine ultrasound for all newborns is not recommended

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Positive Ortolani or Barlow Test (Definite Clunk)

• Immediate orthopaedic referral

• No need for ultrasound or radiographs

• Triple diapering is not recommended (delays effective treatment)

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Equivocal Findings (Soft click or asymmetry)

• Repeat physical examination after 2 weeks

At 2-week follow-up:

• Findings unchanged – orthopaedic referral or ultrasound

• Findings resolved – no further action

• Definite clunk – orthopaedic referral

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Role of Risk Factors When Newborn Exam Is Normal

• Female infants

  • Re-examine hips at 2 weeks

• Positive family history or breech presentation

  • Boys: re-evaluation at 2 weeks

  • Girls:

    • Ultrasound at 6 weeks

    • Radiograph at 4 months

• All breech infants (boys and girls):

  • Consider pelvic radiographs at 4 months to assess acetabular development

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Periodic Hip Examination

• Hip examination must be performed at every well-baby visit

• If DDH is suspected at any age (abnormal exam or parental concern such as difficulty changing diapers), one of the following is required:

  • Focused hip examination in a relaxed child

  • Orthopaedic referral

  • Imaging:

    • Ultrasound if <4 months

    • Radiographs if >4 months

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Assessment in Toddlers and Older Children

• Galeazzi sign: femoral shortening with knees flexed

• Asymmetrical gluteal or thigh folds

• Limited hip abduction

• Gait abnormalities:

  • Limp (unilateral DDH)

  • Waddling gait (bilateral DDH)

Pain is never a symptom of untreated DDH until secondary osteoarthritis develops, typically in adulthood.

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Radiographic Assessment

Hilgenreiner’s Line

• Horizontal line through both triradiate cartilages

• Femoral head ossification center should lie below this line

Perkin’s Line

• Perpendicular line at the lateral edge of the acetabulum

• Femoral head ossification center should lie medial to this line

Shenton’s Line

• Smooth arc along inferior femoral neck and superior obturator foramen

• Should be continuous

Normal Hip

• Ossification center lies in the inferomedial quadrant

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Treatment of DDH

Birth to 4–6 Months

• Pavlik harness

• Keeps hip:

  • Flexed 90–100° (anterior straps)

  • Gently abducted (posterior straps)

• Distance between knees: 3–4 finger breadths (avoid excessive abduction)

• Worn 23 hours/day

• Duration: age at application + 2 months

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After 6 Months

• Arthrogram

• Closed reduction under anesthesia

• Hip spica cast

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Missed DDH After 18 Months

• Requires open reduction

• May need:

  • Femoral osteotomy

  • Pelvic osteotomy

• Outcomes less predictable

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Complications

• Avascular necrosis (AVN) of the femoral head

• Can occur with any form of treatment

• Risk increases with:

  • Excessive abduction

  • Forceful or repeated reductions

• May result in pain and early degenerative arthritis

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Key Take-Home Messages

• DDH is a spectrum, not a single condition

• Clinical examination is the cornerstone of screening

• Imaging complements but does not replace physical examination

• Early diagnosis allows simple and effective treatment

• Delayed or missed DDH leads to complex surgery and poorer outcomes