Acromioclavicular Dislocation or Luxation
Shoulder | Orthopaedics | Acromioclavicular Dislocation or Luxation (Disease)
The acromioclavicular joint, or AC joint, is the shoulder joint, the junction between the acromion which is the part of the scapula that forms the highest point of the shoulder, and the clavicle. The AC joint makes possible raising the arm above the head.
A common injury to the AC joint is dislocation, also known as AC separation or shoulder separation. This is different form a shoulder dislocation, which refers to dislocation of the glenohumeral joint. AC dislocation is particularly common in collision sports such as ice hockey, football, rugby and aussie rules, and is also a problem for those who participate in swimming, horseback riding, mountain biking, biking and snow skiing. The most common mechanism of injury is a fall on the tip of the shoulder or FOOSH (falls on outstretched hand).
Causes and Risk factors
AC dislocations are graded from I to VI, based upon the degree of separation of the acromion from the clavicle with weight applied to the arm. Other injuries sustained from a fall or blow directly on the shoulder may include tears in deltoid and trapezius muscles attached to the clavicle. Shoulder injury from falling onto an outstretched arm is more likely to result in a humeral neck fracture or glenohumeral joint dislocation, and a heavy object falling on the shoulder is more likely to result in a fracture than dislocation.
Diagnosis and Treatment
Grade I and II injuries respond well to non-surgical or conservative treatment with ice, analgesics, and immobilization. Grade IV through VI injuries are treated surgically with open reduction internal fixation (ORIF), a surgical procedure that realigns the bones and reconstructs the ligaments. Screws, wires, or non-absorbable sutures may be used to hold the joint in place while the reconstructed ligaments heal.