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AC Joint Separation

  • Cynthia M. Johnson, MA
Publication Type:


AC Joint Separation

(Acromioclavicular Joint Separation; Shoulder Separation)


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

Shoulder Anatomy.

http://services.epnet.com/getimage.aspx?imageiid=77807780si55550567_105433_1.jpgsi55550567NULLjpgshoulder anatomyNULL\\hgfiler01a\intellect\images\si55550567_105433_1.jpgNULL76NULL2008-12-292843947780_886484Copyright © Nucleus Medical Media, Inc.


This problem 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

Things that may raise the risk of this problem are:

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


Problems may be:

  • Pain and tenderness over the joint
  • Swelling
  • Bruising
  • A popping feeling in the joint
  • A bump on the shoulder


The doctor will ask about symptoms, past health, and how the injury happened. An exam will be done. It will focus on the shoulder. This is often enough to make the diagnosis.

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


Healing time depends on how badly the joint was injured. The goals of treatment are to ease pain and swelling. Medicine can help. Other options are:

  • A sling to prevent the shoulder from moving and give it time to heal
  • Ice packs to ease pain and swelling
  • Exercises to help with strength, flexibility, and range of motion


To lower the risk of this health problem:

  • Do not put yourself at risk for trauma to the shoulder.
  • When playing sports or doing activities:
    • Wear safety equipment
    • Use proper techniques
  • Exercise regularly to maintain strength, movement, and to prevent falls.




  • Acromioclavicular (AC) joint injuries. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/acromioclavicular-ac-joint-injuries.
  • Shoulder separation. Cedars-Sinai website. Available at: https://www.cedars-sinai.org/health-library/diseases-and-conditions/s/shoulder-separation.html.
  • Shoulder separation. Ortho Info—American Academy of Orthopaedic Surgeons website. Available at: https://orthoinfo.aaos.org/en/diseases--conditions/shoulder-separation.


  • Mark D. Arredondo, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.