This is a partial dislocation of the elbow seen with children. A typical story is a child who does not want to move his or her arm after being pulled. The elbow at the top of the radius bone is partially out of place.
No xrays are needed if the story is clear.
The treatment is to push at the top the radius bone while supinating and flexing the arm. Usually a click is felt. Observation post reduction for 10-15 minutes is needed. The goal is to observe the child reach for objects using the affected arm.