Several ligaments surround this joint, and depending on the severity of the injury, one or all of the ligaments may be torn. Severe sprains tear the acromioclavicular and coracoclavicular ligaments.
The acromioclavicular joint is commonly injured when the clavicle is fractured.
Patients have pain and tenderness at the acromioclavicular joint.
Anteroposterior x-rays of both sides of the clavicle are taken.
Acromioclavicular joint sprains are classified based on x-ray findings:
Type I: No joint disruption
Type II: Subluxation with some overlap of the clavicle and acromion
Type III: Complete joint dislocation, usually because the coracoclavicular ligament is torn
Type IV: Posterior displacement of the distal clavicle
Type V: Superior displacement of the distal clavicle
Type VI: Inferior displacement of the distal clavicle
Types IV, V, and VI are variants of type III.