AC Joint Injury


What is an AC Joint Injury?

AC joint injury, or acromioclavicular joint, are quite common. An AC joint injury can result from a hard fall or other traumatic events to the tip of the shoulder. An acromioclavicular joint injury can result in a severe AC sprain, AC fracture or an AC joint separation, which occur when the collarbone (clavicle) separates from the shoulder blade (acromion). An AC joint injury is measured in varying grades.

  • A grade 1 AC joint separation is a mild shoulder separation where the AC ligament is stretched or partly torn.
  • A grade 2 AC joint separation is a partial separation of the AC joint where the AC ligament is completely torn but the coracoclavicular (CC) ligaments are intact.
  • A grade 3 AC joint separation is a complete separation of the joint where the AC ligament and CC ligaments are completely torn, as well as the joint capsule.
  • Grades 4, 5 and 6 AC separations are extremely rare.

The more severe the AC injury the higher riding the clavicle will present at the tip of the shoulder. There could possibly be “tenting” of the skin due to the amount of clavicle displacement in regard to the acromion. Use this link for more information:

AC Joint Injury Symptoms

Symptoms of an injured AC joint will range from mild tenderness to intense, sharp acromioclavicular joint pain that is typically caused by a complete shoulder separation. In a higher grade shoulder injury, a popping sensation will often be heard and prominent shoulder bruising will take place on the skin. Each varying grade of acromioclavicular joint injury requires a specific treatment option. The first step to determining the exact injury grade is a proper diagnosis and examination from Dr. Carofino. After diagnosis, a decision can be reached for proper treatment.

AC Joint Injury Treatment Options

Treatment for a lower grade acromioclavicular joint injury (Grades 1-2) will usually consist of plenty of rest along with the use of pain medications and a shoulder sling. For a more advanced AC joint injury (3-6), surgery will be required to reestablish alignment of the joint and restore proper function to the shoulder. There are numerous shoulder surgery techniques offered to treat an AC joint separation but I prefer to treat my patients with an open incision as in my opinion it provides the best assessment of the joint and less risk of iatrogenic injury to the coracoid process. Typically, I use a donor graft for this reconstruction to reduce additional injury and recovery to the patient.

Please watch this video for more information on how an AC joint is reconstructed.