CNY Orthopedic Sports Medicine, PC: Injury: Acromioclavicular (AC) Separation

Injuries and Conditions: Shoulder: Acromioclavicular (AC) Separation

An AC joint separation commonly results from a fall onto the tip of the shoulder, especially with the arm tucked into the side. A separation occurs when the end of the clavicle pulls apart from the acromion.

The acromioclavicular joint is located between the portion of the shoulder blade known as the acromion and the collarbone. Acromioclavicular (AC) joint separation is a common reference to a partial or complete disruption of the AC joint and surrounding ligaments.

An AC or shoulder separation is a fairly common injury, especially among young adults and athletes. A seperation should not be confused with a dislocation; the two injuries are very distinct, having different signs, symptoms, and treatments.

  • The AC injuries are classified according to the degree of ligament and joint capsule damage. This injury varies in severity from grade I - VI with the classification dependent on the degree of soft tissie disruption and the position of the collarbone(clavicle).
  • The recommended treatment for most AC separations (grade I - III) is non-surgical. Treatment involves application of ice, use of a shoulder immobilizer or specially designed sling, early motion and medication to treat pain and inflammation.
  • Grade IV - VI AC separations are usually treated surgically.
  • Severe Grade III separations may, in rare cases, require surgery to stabilize the shoulder joint while the damaged ligaments heal.
  • If non-surgical treatment does not result in a pain free and functional shoulder after six months, surgery may be considered, which may offer significant improvement for the injured joint.

  • Signs and Symptoms
  • A "bump" may be present over the tip of the collarbone.
  • Symptoms can range from tenderness over the joint to a complete seperation of the AC Joint, with considerable swelling and obvious deformity of the shoulder.
  • Bluish bruising may appear soon after the injury.
  • A popping or tearing sensation inside the injured shoulder may occur with movement.
  • The inability to lift the arm away from the body due to severe pain.


  • Contact the Doctor if ...
  • Pain, swelling or bruising becomes worse despite treatment.
  • Unexpected side effects occur from over the counter or prescription medications.
  • The development of pain, numbness, coldness or weakness in the arm.
  • Unexplained symptoms develop.

  • Common Causes of Injury
  • AC injuries commonly result from a fall onto the side of the shoulder. The traumatic blow to the shoulder temporarily forces the scapula downward away from the collarbone; straining and possibly tearing supporting ligaments.
  • Participation in football or hockey is a common sports-related cause of injury.

  • Expectations of Recovery
  • In most cases, individuals who seek treatment and follow the recommended course of therapy should expect a full recovery.
  • Recovery times range from 2-6 weeks for a mild injury (grade I or II) to 8-10 weeks for a more severe separation (grade III or higher).
  • Prominence of the AC joint or a "bump" on the top of the shoulder is common with the more extensive injuries. This is permanent.
  • A return to normal daily activities is based on the level of pain. Some patients are pain free within three to six weeks of their initial injury. However, a degree of pain or discomfort may be present for between three and six months. Athletes may return to sports in 10-12 weeks.


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