What is the procedure for performing a hip exam, specifically for developmental dysplasia of the hip (DDH) in infants?

Hip Examination for Developmental Dysplasia of the Hip (DDH) in Infants

The proper hip examination for developmental dysplasia of the hip (DDH) in infants requires specific maneuvers including the Ortolani and Barlow tests, assessment of hip abduction, and evaluation for asymmetric skin folds, with different examination techniques needed based on the infant's age.

Age-Specific Examination Techniques

For Infants Under 3 Months

1. Ortolani Test:

   • Position the infant supine with hips and knees flexed at 90°
   • Place your thumb over the inner thigh and fingers over the greater trochanter
   • Abduct the hip while gently lifting the thigh anteriorly
   • A positive test produces a palpable "clunk" as the dislocated femoral head returns to the acetabulum 1

2. Barlow Test:

   • With the infant in the same position, place thumb over femoral neck and fingers over greater trochanter
   • Adduct the thigh while applying gentle posterior pressure to dislocate the femoral head
   • Then abduct the leg while lifting upward to relocate the head
   • A positive test reveals instability with dislocation followed by reduction 1

For Infants Over 3 Months

As the Ortolani and Barlow tests become less reliable after 3 months, focus on:

1. Limited Hip Abduction:

   • Position infant supine with knees and hips flexed
   • Gently abduct both hips simultaneously
   • Limitation or asymmetry of abduction is the most useful clinical sign of DDH 1

2. Thigh Length Assessment:

   • Flex both hips and knees to 90° while supine
   • Compare thigh lengths for asymmetry (Galeazzi sign)
   • Shortening on the affected side suggests DDH 1

3. Skin Fold Asymmetry:

   • Observe for asymmetric thigh or gluteal folds
   • Note that this finding alone has poor specificity 1

For Walking Children

Look for:

• Typical limp with toe-walking on affected side
• Increased lumbar lordosis and prominent buttocks (if bilateral)
• Waddling gait pattern 1

Risk Factor Assessment

During examination, document presence of:

• Female gender (4-8 times higher risk)
• Family history of DDH
• Breech positioning history
• Firstborn status
• History of oligohydramnios 1, 2

Timing of Examinations

The American Academy of Pediatrics recommends hip examinations at:

• 1-2 weeks of age
• 2,4,6,9, and 12 months of age 1, 3

Imaging Recommendations Based on Exam Findings

1. Abnormal physical exam findings:

   • Ultrasound for infants <4 months 1, 4
   • Radiograph for infants >4-6 months 1

2. Normal exam with risk factors:

   • Ultrasound at 4-6 weeks of age 4
   • Radiograph at 4-6 months if ultrasound unavailable 4

Common Pitfalls to Avoid

• Misinterpreting benign "clicks": Distinguish between pathologic "clunks" (positive Ortolani/Barlow) and benign "clicks" that don't indicate instability 1
• Relying solely on skin fold asymmetry: This has poor specificity and should not be the only basis for diagnosis 1
• Single examination only: A normal neonatal exam does not guarantee normal hip development; serial examinations are essential 3
• Improper technique: Ensure the infant is relaxed and comfortable during examination to avoid false-negative results due to muscle tension

Follow-up Recommendations

• If treating with a Pavlik harness, ultrasound is preferred for monitoring treatment response in infants <6 months 1
• Radiographs become more reliable after 4-6 months of age when ossification of the femoral head begins 1
• Even after successful treatment, radiographic follow-up is recommended as deterioration can occur in previously normal hips 5

The hip examination is a critical skill for early detection of DDH, which if untreated can lead to early degenerative joint disease and impaired function. Early detection and treatment significantly improve outcomes and reduce the need for more invasive interventions.