Extremely tight swaddling, in which the hips are forcefully maintained in extension and adduction, increases the risk of DDH. This infant is from the Amazon region of Ecuador, South America
Looseness of the femoral head within the acetabulum is termed instability. Nonconcentric position is subluxation, and deformity of the femoral head and acetabulum is dysplasia. The natural history of instability noted in the first few weeks of life is typically benign, and many cases resolve by 8 weeks of age. Conversely, the natural history of a hip that is subluxated or dislocated at walking age is poor.
Clinical Assessment
Plain radiography becomes useful by 4–6 months of age, when the secondary center of ossification of the femoral head forms. Radiographic hip screening should be considered for the infant with risk factors for DDH or if diagnoses such as congenital short femur, proximal focal femoral deficiency, septic arthritis, or coxa vara are suspected.
The American Academy of Pediatrics recently published their revised guidelines for evaluation and referral of DDH in infants [3]. The authors believe screening is worthwhile to prevent a subluxated or dislocated hip by 12 months of age. The principles of prevention and early detection applied to all levels of health systems are outlined in Box 38.1.
Box 38.1 Principles for Evaluation and Referral of DDH
Physical examination of the infant hip including the Ortolani test is the primary basis of early detection.
Ultrasound to confirm dislocation, subluxation or dysplasia and the effects of treatment. Radiographs to confirm physical exam and for at risk hips when quality ultrasonography is not available (AP pelvic x-ray at 4–6 months).
Minor hip abnormalities on physical examination or imaging can resolve spontaneously, but the infant should be followed up on an individual basis.
Referral to an orthopedic specialist based on an unstable Ortolani exam alone at any age or asymmetric hip abduction after the neonatal period.
Although no screening program can completely eliminate DDH, periodic hip examinations during infancy can greatly reduce the risk of a dislocated hip at 1 year.
Tight swaddling of the hips should always be avoided and is most important for primary prevention [4].