This is a normal x-ray!
Like veggievendor said, this is a kid with sickle cell disease and limited hip ROM, so check the hip for osteonecrosis
I would be concerned for slipped capital femoral epiphysis, as the kid has thigh & knee pain instead of groin pain and has obesity. The referred knee pain is a clue for slipped epiphysis, although slipped epiphysis can lead to avascular necrosis, the necrosis from SCD is more of groin pain.
Just my thought on this question. It doesn't change the answer.
Is this because its a patient with SCD and you are worried about osteonecrosis?