Limited evidence supports the use of an AP pelvis radiograph instead of an ultrasound to assess DDH in infants beginning at 4 months of age.

Rationale
There is limited evidence that an AP pelvis radiograph is preferred to the use of ultrasound to assess for DDH in infants from 4-6 months of age.  This evidence does not distinguish between children with normal or abnormal physical examinations or between children with and without risk factors for DDH. One moderate-strength study investigated the radiographic assessment of every ultrasound positive hip in children four to six months of age. 20 Seventy-four infants with ultrasound positive hips for acetabular dysplasia who met criteria for treatment received an AP pelvis radiograph. Of these 74 infants, 30 were found to have satisfactory acetabular indices and did not receive treatment.

Limitations of this study include the lack of long-term follow-up of the infants to determine if the radiographic assessment altered outcome and failed to address the optimal time of conversion from ultrasound to radiographic assessment in infants with DDH.

Risks and Harms of Recommendation:
Radiographs involve exposure to ionizing radiation.
 
  1. (20) Tudor A, Sestan B, Rakovac I et al. The rational strategies for detecting developmental dysplasia of the hip at the age of 4-6 months old infants: a prospective study. Coll Antropol 2007;31(2):475-481.