Rockwood AC joint injury

Rockwood 1984XRTrauma

Figure · click to enlarge

Rockwood types I–VI. Image: Andrew Murphy, Radiopaedia.org, CC BY-NC-SA

Grades acromioclavicular injury by which ligaments are torn and where the clavicle moves. Compare coracoclavicular (CC) distance with the uninjured side.

Type	Ligaments	Radiographs	Usual management
I	AC ligament sprain; CC intact	Normal	Non-operative
II	AC torn; CC intact or sprained	AC widening, mild clavicle elevation; CC distance normal	Non-operative
III	AC and CC torn	Clavicle elevated; CC distance increased 25–100%	Debated
IV	AC and CC torn	Clavicle displaced posteriorly into or through trapezius (axillary view or CT)	Operative
V	AC and CC torn; deltotrapezial fascia stripped	CC distance increased 100–300%	Operative
VI	AC and CC torn	Clavicle displaced inferiorly, subacromial or subcoracoid	Operative

Pearls

Normal CC distance is roughly 11–13 mm; a side-to-side difference over about 5 mm suggests CC ligament disruption.
Type IV is easy to miss on AP views; get an axillary view or CT when the AP looks near-normal but the exam does not.

Sources

Rockwood CA Jr. Injuries to the acromioclavicular joint. In: Rockwood CA Jr, Green DP, eds. Fractures in Adults. 2nd ed. Philadelphia: Lippincott; 1984:860–910.

Radessential summarizes published classification systems for practicing radiologists. Summaries are condensed; confirm details against the cited source before relying on them for patient care.