I heard of a case of a child who had severe nerve problems in his arm after he dislocated his elbow. This wasn't seen until a few weeks after the accident and then it wasn't dealt with for several more weeks. How could the doctors not tell right away and why would they wait?
When a child (or adult) dislocates his elbow, there is always the possibility that one of the nerves that travels through the elbow gets trapped in a position it isn't normally. However, this can't be seen on an x-ray or any of the usual tests done with a suspected dislocated elbow. It is only during follow up that doctors may see some signs that there is a nerve entrapment and it may not be very clear at first. If they suspect the nerve has been trapped, they may opt to wait a short while to see if the problem will resolve itself on its own. If it doesn't, then they may step in and work on the problem - usually through surgery.