Dislocation in acromioclavicular joint - Rockwood classification of AC dislocation

Rockwood classification divides dislocations in AC joint into six grades. It is an extension of the previous classification by Tossy et al. Normal width of AC joint is considered 1-3mm, widened AC joint has >7mm in men or >6mm in women.

Grade Description
Grade I sprain of the acromioclavicular (AC) ligaments
Grade II complete rupture of the AC ligaments
Grade III complete rupture of the AC and coracoclavicular (CC) ligaments
Grade IV complete rupture of the AC and CC ligaments with displacement of the clavicle posteriorly
Grade V complete rupture of the AC and CC ligaments with gross displacement of the AC joint and detachment of the deltoid and trapezius muscles
Grade VI inferior subcoracoid displacement of the distal end of the clavicle

AC = acromioclavicular, CC = coracoclavicular


1. Williams GR, Nguyen VD, Rockwood CR. Classification and radiographic analysis of acromioclavicular dislocations. Appl Radiol 1989;Feb:29–34
2. Mazzocca AD, Arciero RA, Bicos J. Evaluation and Treatment of Acromioclavicular Joint Injuries. Am J Sports Med. 2007 Feb 1;35(2):316–29.