AC Joint Separation Explained

Since the shoulder joint has the widest range of motion, it also is the most prone to injury from sports incidents, falls, or overuse.

What is an AC joint injury?

The acromioclavicular (AC) joint is formed between the collarbone (clavicle) and the tip of your shoulder blade (scapula). You can feel it by putting your hand on top of your shoulder and locating a bony bump.  You may sometimes hear an AC joint separation referred to as a shoulder separation, but it doesn’t actually involve the shoulder. Instead, it occurs when the collarbone separates from the shoulder blade.  AC joint injuries range in severity from a slight dislocation to a complete separation, and treatments can range from at-home treatments to AC joint surgery.  A slight dislocation is the most common type and causes the AC ligament to be stretched or partially torn. An AC joint may also be partially dislocated, with a completely torn AC ligament.

What are its symptoms?

The symptoms you may experience with an AC joint injury depend on the severity of your injury.

If you have a partial dislocation, you may have the following:

• Tenderness when you touch the joint

• Bruising

• Minor pain when you more your arm

If your AC joint is partially dislocated, you may experience the following:

• Moderate to severe pain

• Swelling

• Pain when you move your arm

• Clavicle moves when it’s pushed

• Painful to the touch

Finally, if you have a completely separated AC joint, you may have the following symptoms:

• Tendency to support your elbow and hold your arm close to your side

• Arm hurts with any type of movement

• Popping sound when you move your joint

• Swelling

• A bump on top of your shoulder, or the outer end of your collarbone may look out of place

• Unstable joint