Type I: Sprain of the acromio-clavicular or coracoclavicular ligament
Type II: Subluxation of the acromioclavicular joint associated with a tear of the acromioclavicular ligament; coracoclavicular ligament is intact.
Type III: Dislocation of the acromioclavicular joint with injury to both acromioclavicular and coracoclavicular ligaments
Type IV: Clavicle is displaced posteriorly through the trapezius muscle
Type V: Gross disparity between the acromion and clavicle, which displaces superiorly
Type VI: Dislocated lateral end of the clavicle lies inferior to the coracoid
Provide an explanation for key principles and pertinent aspects of the classification
Provide the citation for the landmark article and recent review articles describing the classification