Case 3 Answer

Does this image help?

Answer: Posterior shoulder dislocation

because posterior dislocations are generally straight backwards, they can be difficult to notice on the frontal exams if you aren’t looking for them. Here we see:

absent external rotation

loss of normal glenohumeral overlap

widened glenohumeral joint

light bulb sign-ish?

But always note when the frontal views show both humeral heads in either external rotation (anterior dislocation) or internal rotation (posterior dislocation).