AC Joint Separation

(Acromioclavicular Joint Separation; Shoulder Separation)

A-C Joy-N-T Sep-ar-a-shun



The acromioclavicular (AC) joint is between the upper part of the shoulder blade and the collarbone. AC joint separation happens when the ligaments of this joint become damaged or torn. This causes a separation between the shoulder blade and the collarbone.

Shoulder Anatomy

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AC joint separation is caused by a trauma to the shoulder such as:

  • Falling directly onto the shoulder—most common cause
  • Being hit on the point of the shoulder blade
  • Falling on an outstretched arm

Risk Factors

Risk Factors

Factors that may increase your chance of an AC joint separation include:

  • Playing certain sports, such as football, hockey, or lacrosse
  • Sports that may involve falls like cycling, skiing, or gymnastics
  • Increased age



Symptoms may include:

  • Tenderness or pain over the joint
  • Swelling
  • Bruising
  • A popping sensation in the joint
  • A bump on the shoulder



You will be asked about your symptoms, medical history, and related accident. A physical exam will be done. It may include range-of-motion tests of the shoulder. The diagnosis can be made when there is an obvious deformity of the joint.

Images may be taken of your shoulder. This can be done with x-rays.



Talk with your doctor about the best treatment plan for you. Treatment depends on the degree of your AC joint separation. Options include:

Basic Support

A support, such as a sling, will be given to prevent the shoulder from moving and reduce pain as it heals. Applying an ice pack will also help reduce swelling and promote proper healing.

Your doctor may also advise over-the-counter or prescription pain medication.


Surgery may be needed if the AC joint separation is severe. Surgical options include:

  • Trimming back the end of the collarbone so that it does not rub against the shoulder blade
  • Reconstructing the ligaments that attach to the underside of the collarbone


You may be referred to a physical therapist to learn exercises to strengthen and/or stabilize the area.



To help reduce your chance of AC joint separation:

  • Do not put yourself at risk for trauma to the shoulder.
  • Exercise regularly to maintain strength, mobility, and to prevent falls.
  • Learn the proper technique and wear protective equipment for exercise and sporting activities.

To help reduce falling hazards at work and home:

  • Clean spills and slippery areas right away.
  • Remove tripping hazards such as loose cords, rugs, and clutter.
  • Use non-slip mats in the bathtub and shower.
  • Install grab bars next to the toilet and shower or tub.
  • Put in handrails on both sides of the stairways.
  • Walk only in well-lit rooms, stairs, and halls.
  • Keep flashlights on hand in case of a power outage.


Ortho Info— American Academy of Orthopaedic Surgeons

Sports Med—American Orthopaedic Society for Sports Medicine


Canadian Orthopaedic Association

Canadian Orthopaedic Foundation


The AC (acromioclavicular) joint. Southern California Orthopedic Institute website. Available at:
Accessed December 3, 2013.

AC joint injuries. American Orthopaedic Society for Sports Medicine website. Available at:
Accessed December 3, 2013.

Acromioclavicular (AC) joint separation. Cedars-Sinai website. Available at:
Accessed December 3, 2013.

Acromioclavicular (AC) joint injuries. EBSCO DynaMed website. Available at:
Updated September 6, 2012. Accessed December 3, 2013.

Acromioclavicular joint separation. Orthogate website. Available at:
Accessed December 3, 2013.

Shoulder separation. American Academy of Orthopaedic Surgeons Ortho Info website. Available at:
Updated October 2007. Accessed December 3, 2013.

Last reviewed December 2014 by Michael Woods, MD
Last Updated: 12/20/2014

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