Rockwood classification of acromioclavicular joint injury

A.Prof Frank Gaillard ◉ et al.

Acromioclavicular joint injuries are classified most commonly using the 6-grade system described by Rockwood (1998) ³. This is a modification of the earlier 3-grade classification system described by Allman (1967) ² and Tossy (1963) and at the time of writing (June 2016) remains the most recent system for acromioclavicular joint injury assessment.

It takes into account not only the acromioclavicular joint itself, but also the coracoclavicular ligament, the deltoid and trapezius muscles and the direction of dislocation of the clavicle with respect to the acromion. Essentially grades IV, V and VI are variants of grade III ⁶.

type I: clavicle not elevated with respect to the acromion
- AC ligament: mild sprain
- CC ligament: intact
- joint capsule: intact
- deltoid muscle: intact
- trapezius muscle: intact
type II: clavicle elevated but not above the superior border of the acromion
- AC ligament: ruptured
- CC ligament: sprain
- joint capsule: ruptured
- deltoid muscle: minimally detached
- trapezius muscle: minimally detached
type III: clavicle elevated above the superior border of the acromion but coracoclavicular distance is less than twice normal (i.e. <25 mm)
- AC ligament: ruptured
- CC ligament: ruptured
- joint capsule: ruptured
- deltoid mucle: detached
- trapezius muscle: detached
type IV: clavicle displaced posteriorly into trapezius
- AC ligament: ruptured
- CC ligament: ruptured
- joint capsule: ruptured
- deltoid muscle: detached
- trapezius muscle: detached
type V: clavicle is markedly elevated and coracoclavicular distance is more than double normal (i.e. >25 mm)
- AC ligament: ruptured
- CC ligament: ruptured
- joint capsule: ruptured
- deltoid muscle: detached
- trapezius muscle: detached
type VI: clavicle inferiorly displaced behind coracobrachialis and biceps tendons, which is rare
- AC ligament: ruptured
- CC ligament: ruptured
- joint capsule: ruptured
- deltoid muscle: detached
- trapezius muscle: detached