The acromioclavicular ligament caps the AC joint, providing the primary resistance against anteroposterior clavicular displacement relative to the acromion. It is disrupted in all AC joint separations (Rockwood Grade I and above), while the coracoclavicular ligaments (which resist vertical displacement) remain intact in Grade I-II injuries. AC joint sprains are classified by the degree of ligament disruption.
| Origin | Acromion process (lateral border) |
|---|---|
| Insertion | Lateral clavicle |
| Actions | Primary horizontal stabiliser of the AC joint — resists anteroposterior clavicular displacement |
|---|
Grade I AC sprains (AC ligament sprain, CC ligaments intact) are managed conservatively. Grade III injuries (both AC and CC ligaments torn, clavicle displaced superiorly) are controversial — most are managed non-operatively in sedentary patients, surgically in active overhead athletes. Grade IV-VI injuries (posterior, inferior, or locked dislocation) require surgical reduction.
Acromioclavicular and coracoclavicular ligament disruption producing superior clavicular displacement classified by Rockwood grade and managed operatively for Grade IV-VI.
