Acromioclavicular separation. This young man fell directly onto his left shoulder. His normal right shoulder has been provided for comparison – note the appearance of the AC joint. On the left, there is a wide gap between the distal clavicle and the acromion, and the distal end of the clavicle has become displaced superiorly relative to the position of the acromion. This is a type II sprain of the AC joint. To see how we classify AC joint injuries, click here.