Acromioclavicular joint injuries.

Acromioclavicular joint injuries, including sprains and dislocations, are common shoulder problems treated by orthopaedic surgeons. The classification of acromioclavicular joint injuries comprises six grades, according to the degree of ligamentous disruption and displacement. Grades I and II are generally treated nonoperatively, whereas types IV, V, and VI are treated surgically. Treatment for grade III injuries remains controversial. Fractures of the distal aspect of the clavicle have been divided into three types. Type I fractures are stable and require brief immobilization. Type II fractures are unstable and require surgical fixation. Type III fractures often require late surgery for acromioclavicular arthritis.