A 3-year-old girl presents to the urgent care center with right hip pain. She has no fever, and the parents report there was no trauma. The child has a limp and reproducible pain on external rotation of the right hip.
White blood count is 11,900 with 40.7% lymphs. The erythrocyte sedimentation rate (ESR) is 3 mm/hour. The x-ray (Figure 1) shows fluid around the right hip joint; this finding was confirmed by ultrasound.
View the x-ray and consider what your next steps would be. Resolution of the case is described on the next page.