An AC joint separation, also called a shoulder separation, is a sprain or tear of the ligaments that hold your collarbone to the top of your shoulder blade. It usually happens from a fall straight onto the point of the shoulder.
Most people recover WITHOUT surgery.
A mild separation settles in about 2 weeks, a moderate one in about 6, and a complete one can take up to 3 months. A sling for the first week or two is for comfort.
The bump on top of your shoulder often STAYS. That’s the collarbone sitting a little higher than before. It looks alarming, but most people, including professional athletes, get back to normal use with the bump still there.
What the AC joint is
- The AC joint (acromioclavicular joint) is where the outer end of your collarbone meets the acromion, the bony tip of your shoulder blade. You can feel it as a small ridge on top of the shoulder
- Two sets of ligaments hold it: small ones around the joint itself, and stronger ones a little further in that tie the collarbone down to the shoulder blade
- A separation is not a dislocation. In a dislocation, the ball of the arm comes out of the socket. That’s a different injury. See will a dislocated shoulder pop out again?
- It’s also not a broken collarbone, though the same kind of fall can cause either, and an X-ray tells them apart. See broken collarbone recovery
The grades, and what they mean for you
- Grade 1: the small ligaments are sprained. The collarbone hasn’t moved. Tender on top of the shoulder, no bump
- Grade 2: the small ligaments are torn and the stronger ones are sprained. The end of the collarbone rides up a little, leaving a small bump
- Grade 3: both sets of ligaments are torn. The bump is bigger and easy to see. This is the grade where treatment is most debated
- Grades 4 to 6: less common. The collarbone is pushed well out of place, backward, very high, or downward, often with damage to the muscles over it. These usually need surgery
Recovery time by grade
- Grade 1: about 2 weeks back to normal activity and most sports
- Grade 2: about 6 weeks
- Grade 3 without surgery: up to about 3 months. Most people are doing everyday tasks well before that, and contact sport comes last
- After surgery: a sling for about 4 weeks, then several months of rehab. Return to sport is typically around 4 months or later
These are typical ranges. Your doctor may give you different targets. Use theirs.
Week by week without surgery
- First few days: sling for comfort, ice for 15 to 20 minutes at a time, and pain relief as your doctor or pharmacist advises. Take the arm out to move it gently below shoulder height
- Weeks 1 to 2: most people are out of the sling. Keep moving the shoulder within comfort. Stiffness from keeping it still for too long is a bigger problem than the separation itself
- From about week 2: strengthening starts, beginning with the rotator cuff and shoulder blade muscles. These muscles help hold the joint steady now the ligaments can’t
- Later: overhead work, push-ups, bench press and carrying heavy loads come back last. They put the most strain directly through the AC joint
The bump is cosmetic. How the shoulder works is what you rebuild.
The bump that stays
- Why it stays: the torn ligaments heal with scar tissue, and the collarbone settles in its new, slightly higher position
- It doesn’t mean it healed wrong. Strength and movement usually return fully with the bump in place
- Some people notice it on backpack straps or when lying on that side. That tends to ease over the first few months
- Surgery to flatten the bump for looks alone is rarely worth it. The operation leaves a scar and carries its own risks, and the bump can partly come back
When surgery is considered
- Grades 4 to 6: surgery is usually recommended because the collarbone is badly out of place
- Grade 3: most people start without surgery. A minority still have pain or weakness with overhead use after 2 to 3 months and then go on to an operation. People who have the operation later still tend to do well, so trying rehab first rarely closes a door
- People who might choose earlier surgery for grade 3 include heavy manual workers who use the arm overhead and some overhead athletes. That’s a conversation with your surgeon
- Pain that lingers years later can come from wear in the joint. A cortisone shot can help settle it, and trimming the end of the collarbone is an option if nothing else works. See cortisone shot side effects
The AAOS OrthoInfo guide to shoulder separation has diagrams of each grade if you want to see where the ligaments sit.
What’s normal
- Bruising over the top of the shoulder that spreads over the first week
- A click or grind on top of the shoulder with some movements, usually painless
- Pain reaching across your body, like washing the opposite armpit or doing a seatbelt. This squeezes the AC joint and is often the last thing to settle
- Aching after a busy day for a few months
Go to the emergency department if
- The collarbone looks pushed far out of place, or the skin over it is tented, broken or turning pale
- Your arm goes numb, cold, pale or weak after the fall
- You have trouble breathing or pain in your chest after the injury
Get it checked if
- You haven’t had an X-ray and the bump is new after a fall
- Pain is still stopping you sleeping after 2 weeks
- You can’t lift the arm, or overhead use still hurts after 2 to 3 months of rehab
- The bump seems to be getting bigger
The bump usually stays. The strength comes back if you work for it.