Diagnostics

• Physical examination must be performed at every well-baby visit for up to 6 months

• Screening with imaging is recommended up to 6 months of age only if one or more of the following risk factors are present

  • Breech presentation at birth

  • Positive family history of DDH

  • Clinical features of DDH

• Hip ultrasound: imaging of choice in all infants younger than 4 months

  • Alpha angle < 60°

  • Beta angle > 55°

• Pelvic x-ray (in AP and frog leg lateral view): imaging of choice in infants older than 4 months (when cartilage begins to ossify)

  • Findings of hip dislocation

    • Interrupted Shenton's line

    • The ossified nucleus of the femoral head lies at or above Hilgenreiner line

    • The ossified nucleus of the femoral head lies at or lateral to Perkin line

  • Findings of acetabular dysplasia

    • Acetabular angle > 30° after 4 months

    • Center-edge angle < 19° in the age group 6–13 years, or < 25° in children older than 14 years

• Arthrogram: indicated following closed reduction to ensure successful reduction (see “Treatment” below)

• Hip CT: imaging of choice to follow up patients with a hip spica

• Hip MRI: not used in the diagnosis of DDH

Ultrasound is the imaging technique of choice for diagnosis of DDH in infants less than 4 months while x-ray is the imaging modality of choice for infants older than 4 months.