Classification of Neer and Rockwood for Injury to the Acromioclavicular Joint

Neer and Rockwood classified injuries to the acromioclavicular joint. This is an extension of the classification of Tossy et al (see below).

Parameters:

(1) acromioclavicular ligament

(2) acromioclavicular joint

(3) coracoclavicular ligament

(4) coracoclavicular interspace

(5) deltoid and trapezius muscle insertion

Parameters	Type I	Type II
acromioclavicular ligament	sprain	disrupted
acromioclavicular joint	normal	wider and displaced slightly upward
coracoclavicular ligament	normal	sprain
coracoclavicular interspace	normal	normal
deltoid and trapezius muscles	normal	minor disruption

Parameters	Type III	Type IV
acromioclavicular ligament	disrupted	disrupted
acromioclavicular joint	displaced upward	displaced posterior
coracoclavicular ligament	disrupted	partial or complete disruption
coracoclavicular interspace	25 - 100% greater than opposite (normal) side	25 - 100% greater than opposite (normal) side
deltoid and trapezius muscles	detached from distal clavicle	detached

coracoclavicular interspace increase =

= ((coracoclavicular interspace affected side) - (coracoclavicular ligament opposite side)) / (coracoclavicular ligament opposite side) * 100%

Parameters	Type V	Type VI
acromioclavicular ligament	disrupted	disrupted
acromioclavicular joint	displaced up	displaced down
coracoclavicular ligament	disrupted	intact or disrupted
coracoclavicular interspace	100 - 300% greater than opposite (normal) side	clavicle located below
deltoid and trapezius muscles	detached	intact, stretched or detached

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