In infants with developmental dysplasia of the hip, which finding is considered diagnostic?

• A. A palpable clunk is considered diagnostic.
• B. They usually have other orthopedic ailments.
• C. Most have some congenital orthopedic anomaly.
• D. There is often pain in the hip when the diaper is changed.

Answer: (A)

In infants, a palpable clunk when the hip is gently reduced into place—the Ortolani sign—is the finding that confirms developmental dysplasia of the hip. This clunk means the dislocated femoral head can be reduced back into the acetabulum, which is highly specific for DDH. The other statements describe non-specific features: a positive Barlow test is a screening finding for hips that are dislocatable but not diagnostic by itself; many infants with DDH do not have other orthopedic conditions or congenital anomalies, and hip pain with diaper changes is not characteristic of DDH in newborns.