Final answer:
To correct the positioning on an AP elbow with lateral rotation and a slightly superimposed radial head over the proximal ulna on the first effort, the elbow joint should be rotated medially.
Step-by-step explanation:
In order to correct the positioning on an AP elbow with lateral rotation when the radial head is slightly superimposed over the proximal ulna on the first effort, the elbow joint should be rotated medially. This means that the forearm should be moved towards the midline of the body. By doing so, the radial head will no longer be superimposed over the proximal ulna and the positioning will be corrected.