AC Joint Injuries Symptoms & Causes

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How does arthritis affect the AC joint?

Arthritis is a condition characterized by loss of cartilage in the joint.

  • Like arthritis at other joints in the body, it is characterized by pain and swelling, especially with activity.
  • Arthritis can lead to formation of spurs around the joint. These spurs are a symptom of the arthritis and not the primary cause of the pain.
  • Motions that aggravate arthritis at the AC joint include reaching across the body toward the other arm.
  • AC joint arthritis is common in weight lifters, especially with the bench press, and to a lesser extent military press.
  • AC joint arthritis may also be present when there are rotator cuff problems.

What is an AC joint separation

When the AC joint is separated, the ligaments connecting the acromion and collarbone are damaged, and the two structures no longer line up correctly. AC separations are graded depending upon which ligaments are torn and how badly they are torn. 

  • Grade I Injury –  the least damage is done, and the AC joint still lines up.
  • Grade II Injury – damage to the ligaments that reinforce the AC joint. These ligaments are only stretched but not entirely torn. When stressed, the AC joint becomes painful and unstable.
  • Grade III Injury – AC and secondary ligaments are completely torn and the collarbone is no longer tethered to the shoulder blade, resulting in a visible deformity.

What causes arthritis of the AC joint?

Arthritis of the AC joint mainly affects older adults. Your child may be at risk for arthritis of the AC joint due to:

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