What Is an AC Joint Sprain?

Your acromioclavicular (AC) joint sits at the top of the shoulder, where your collarbone meets your shoulder blade. It's held in place by a set of ligaments. A fall directly onto the shoulder — or onto an outstretched arm — can sprain or tear these ligaments, causing pain and tenderness right at the point of the shoulder.

Understanding the Grades

AC joint injuries are graded I–VI based on how much the ligaments are damaged:

  • Grade I–II — a sprain or partial tear; the joint stays essentially in position

  • Grade III — both major ligaments tear; the collarbone sits visibly higher, often called a “bump”

  • Grade IV–VI — more severe displacement, sometimes with muscle detachment; less common and usually more involved

Surgery Is the Exception, Not the Rule

Grades I and II are treated conservatively in the large majority of cases. Even for Grade III, current evidence shows that outcomes with focused rehab are often comparable to surgery at one year, so the decision is individualized rather than automatic. Higher grades (IV–VI) are more likely to need surgical stabilization.

Your Recovery Timeline

  1. Weeks 1–2: Protect it — brief sling use, icing, and pain control while irritation settles.

  2. Weeks 3–6: Restore motion — the sling comes off and gentle range-of-motion work begins.

  3. Weeks 6–12: Rebuild strength — progressive rotator cuff and shoulder-girdle strengthening.

  4. Months 3–6: Return to sport — power and contact-specific training once strength is back.

Bottom line: Most AC joint sprains — even some higher-grade ones — recover well without surgery. Progressing your motion and strength on the right schedule matters more than the grade on paper.