A classification of acute acromioclavicular dislocation: a clinical, radiological and anatomical study.

Forty-eight patients with acute acromioclavicular dislocation were assessed clinically and radiologically before random allocation to non-operative management (28) or open reduction and coracoclavicular screw fixation (20) and followed for a minimum of 4 years. In 6 patients, late salvage surgery was required, the results of which were inferior to early operative intervention. Early surgery also gave better results than non-operative treatment in severe disruptions which could be identified in the acute stage. Three types of acromioclavicular dislocation which have predictable clinical outcomes could be distinguished on radiographs. When treated non-operatively, type A dislocations (19 per cent) may develop painful subluxation, type B (68 per cent) remain dislocated but retain sufficient muscle attachment to avoid fatigue on activity, and type C (12 per cent) leave a weak and unsightly shoulder. In type C dislocations, the clavicle is displaced 2 cm or more from the acromion on plain anteroposterior radiographs and the attached origin of the anterior deltoid is avulsed. Type C dislocations may benefit from early operative reconstruction.