Acromioclavicular (AC) Joint Injuries: Dislocations, Separations, & Sprains

AC Injuries

Acromioclavicular separations or sprains can vary in severity, depending on the extent of injury to the stabilizing ligaments and capsule.

For many AC joint injuries, it is common to see only a partial tear of the acromioclavicular ligament. This is what is known as a grade 1 injury to the AC joint. Grade 1 AC joint injuries, also frequently called sprains, are the least severe type of AC joint injury. 

Grade 2 AC joint injuries, commonly referred to as a “separated shoulder”, occur when the acromioclavicular and/or coracoclavicular ligament is partially torn. Grade 2 AC joint injuries typically result in subluxation or partial displacement or the shoulder, which can be confirmed through x-rays.

Grade 3 AC joint injuries occur when the force of injury is enough to completely tear both the acromioclavicular & coracoclavicular ligaments, and the shoulder capsule. Grade 3 AC joint injuries are true dislocations of the AC joint, and will often times be referred to as a “dislocated shoulder”. 

Who

Athletes are at the highest risk for AC injuries, specifically football and hockey players, as these sports put a lot of stress on the shoulders. Athletes who suffer an AC joint injury will often leave the playing area holding their arm close to their side.

It’s very important to determine the exact mechanism of the injury when dealing with the AC joint. Did the athlete fall on the outstretched arm, or receive a severe blow to the acromial area (arm)? When examining the area, your physician will rule out pain from contusion or other injuries by manipulating the shoulder joint. Occasionally, an obvious deformity or easily detected abnormal motion of the AC joint will make it easier to diagnose the injury. Generally speaking, less severe AC joint injuries tend to be more difficult to diagnose. In many cases, patients with less severe AC joint injuries will have to be put through a variety of motion tests to determine the proper diagnosis.

Management

Treatment of AC joint injuries depends on the severity. Grade 1 and 2 injuries to the AC joint can often be treated successfully with a sling for 2 to 4 weeks, with patients returning to activity when pain is alleviated. Recovery is often supplemented with physical therapy to restore normal range of motion and strengthen the upper extremities. The treatment of grade 3 AC joint injuries tends to be more complex, and varies on a case by case basis depending on the patient and severity of the dislocation.

Grade 3 AC joint injuries can be treated aggressively with open reduction surgery, or conservatively with non-surgical methods. When surgery is performed, it is usually directed at reconstruction of the conoid and trapezoid ligaments (coracoclavicular ligaments). It is important to discuss both of these options with your doctor before deciding which treatment approach is right for you. 

Return to Activity

It is crucial that athletes not return to sport until they have full range of nonpainful motion, no tenderness upon direct palpation of the acromioclavicular joint, and no pain when manual traction is applied.

Prognosis

The prognosis of AC joint injuries is very good, obviously better for the lower grade injuries (sprains and separations). However, even grade 3 injuries (dislocations) will heal well if the appropriate treatment is applied, and enough rehabilitation & rest is allowed.