Hip Hop

A healthy six month old infant comes for a well child check. She had a breech presentation at birth but was delivered vaginally without complication. Otherwise, she is up to date on her vaccinations and sees you regularly. The infant is calm, not crying, and supine on the examining table with hips flexed to 90 degrees in neutral rotation. You grasp her right thigh and gently adduct the hip with posteriorly directed pressure. You note posterior sliding and a palpable "clunk." You then abduct the hip and lift anteriorly and feel another clunk. Here's an X-ray:



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