An AC sprain in your shoulder is an injury to the acromioclavicular joint —the small joint at the top of the shoulder where the collarbone meets the shoulder blade. It usually happens when the ligaments there are stretched or torn, often after a fall or a direct hit to the shoulder.

Quick Scoop

Common signs include:

  • Pain at the top of the shoulder.
  • Swelling or bruising.
  • Tenderness when you touch the area.
  • A visible bump or change in shoulder shape in more serious cases.
  • Pain when lifting your arm or reaching across your body.

Why it happens

It often comes from:

  • Falling directly onto the shoulder.
  • Falling onto an outstretched hand.
  • A collision or blunt impact to the shoulder.

How serious it can be

AC sprains range from mild ligament stretching to a more severe separation, where the bones are pulled out of alignment. Mild cases may heal without surgery, while more severe injuries need medical evaluation and sometimes surgery.

When to get checked

You should get medical care if you have:

  • Major pain.
  • A visible bump or deformity.
  • Trouble moving the arm.
  • Numbness, weakness, or severe swelling.

If you want, I can also explain how to tell an AC sprain from a rotator cuff injury or shoulder dislocation.