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What is a Shoulder AC Joint Sprain/Separation?

The shoulder is made up of the humerus (upper arm bone), the scapula (shoulder blade), and the clavicle (collarbone). The location where the clavicle meets the scapula (acromion) there is a joint called the acromioclavicular (AC) joint. Surrounding this joint is a capsule and ligaments that help give stability to the joint. When the capsule or ligaments are stretched or torn at the AC joint it is referred to as a shoulder separation. This separation can create instability where the clavicle meets the shoulder blade. This injury is commonly confused with a shoulder dislocation. A shoulder dislocation is when there is a disruption between the humerus (the ball) and the glenoid (the socket) whereas the shoulder separation is a disruption between the acromion and the clavicle.


  • Direct trauma to the lateral (outside) aspect of the shoulder (most commonly resulting from a check into the boards in ice hockey or collision in football or lacrosse)
  • Falling directly on the shoulder

Signs & Symptoms

  • Shoulder pain to the superior (top) shoulder
  • Arm weakness or a “heavy” shoulder feeling
  • Bruising or swelling to the superior shoulder
  • Decreased range of motion of the shoulder
  • A noticeable bump on the top of  the shoulder


Initial treatment of a shoulder separation is rest and ice. A sling is usually used to allow for the shoulder to relax and provide some comfort. After the pain and swelling subside, beginning physical therapy to regain motion and strength gradually is common. If all goes well, it is common to have a complete recovery back to all sports following a shoulder separation. This usually occurs anywhere from a few weeks to a few months depending on the severity of the injury and the sport. There may always be a noticeable bump on the shoulder following this injury, but if motion and strength are normal and there is no pain, it is nothing to worry about. If pain continues after following the non-surgical course of physical therapy, surgery to repair or reconstruct the torn ligaments may be warranted.

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