21 year old man presented with shoulder pain after falling off his bike. What is your diagnosis?

Acromioclavicular dislocation- the key to the diagnosis is knowing that the undersurface of the distal clavicle and the undersurface of the acromion should normally align with each other . Other clues to the diagnosis include widening of the distance between the clavicle and acromion, and of the distance between the clavicle and the coracoid process of the scapula. Anterior glenohumeral joint dislocation is the most common form of shoulder dislocation. Posterior glenohumeral dislocation is uncommon but should be suspected in patients with shoulder pain following a seizure.