OK, I will admit I was a tad misleading on this (and I know that clinicians NEVER are!) but I wanted to get some thinking going on.  A lot of people got the obvious finding - Left hip dislocation. But why? Look at the left acetabulum and compare it to the right. Very different, correct? The left acetabulum is EXTREMELY shallow (I think the right may be minimally shallow as well). I don’t see a cortical break or displaced bony fragment. And what about the the left femoral head? Is is normal? No. What about it’s position? Dislocations of the hip are generally anterior or posterior and this is cranial ( or Proximal). 

Answer: Congenital Hip Dysplasia

In fact the left hip is so dysplastic that the femoral head is dislocated (and likely chronically due to the malformed femoral head). This is where your experience can be helpful when the ER docs are trying to reduce something that is chronic and not reducible.

I have actually seen several of these cases recently and I wanted to share this so everyone can see it. 

Good write up of NUMEROUS hip pathology but check out the last section for information relating specifically to CHD: http://radiographics.rsna.org/content/20/suppl_1/S3.full