Table 1 Rockwood Classification of Acromioclavicular Joint Injury

I

• AC ligament sprain with ligaments intact

• No displacement or instability

• Tenderness at ACJ

• Provocative tests positive (cross body adduction, etc)

• No obvious radiographic abnormality

II

• Ac ligaments torn

• CC ligaments sprained but intact

• ACJ subluxation/displacement with provocative stress

• Can show subtle distal clavicle elevation, but no obvious separation

III

• Disruption of AC and CC ligaments

• A/P and superior/inferior instability

• Superior displacement of the distal clavicle

• Acromion and shoulder girdle inferior to distal clavicle

• Radiographs may show up to 100% or greater increase in CC distance

IV

• Disruption of AC and CC ligaments

• Posterior displacement of distal clavicle through trapezius

• Palpable distal clavicle posteriorly through trapezial fascia

• Also associated with anterior SC joint injury/dislocation

• Subtle findings on AP/Zanca view

• Critical to evaluate for posterior distal clavicle displacament on axillary view

V

• Disruption of AC and CC ligaments

• Significant displacement of acromion/scapula due to weight of the extremity

• Gross superior displacement of distal clavicle and inferior translation of acromion/scapular complex

• Can protrude through trapezial/deltoid fascia and tent skin

• CC distance grossly increased, greater than 100%

VI

• Inferior displacement/dislocation of distal clavicle

• Can be displaced subacromial or subcorocoid

• Can palpable defect and displaced distal clavicle

• Neurovascular exam critical to rule out associated neurovascular compromise

• Detect distal clavicle in subcorocoid/subacromial position