AC Joint Dislocations

The acromioclavicular (AC) Joint is commonly injured when a person falls onto their shoulder.

The AC Joint consists of three ligaments:

• acromioclavicular ligament (AC)
• coracoacromial ligament (CA)
• coracoclavicular ligament (CC)

Injuries to this joint are classified as Type I – Type VI and involve sprain or tears of the AC or CC ligaments

• Type I – Is a sprain of the joint without complete tear of either the AC or CC ligament
• Type II – Does not show significant elevation of the lateral end of the clavicle but is due to a tear of the AC ligament.
• Type III – Results from tears in the AC and CC ligament. Noted by > 5 mm elevation of the AC joint.
• Types IV – VI : are associated with complications of a Type III injury.