An Acromioclavicular (AC) joint sprain, often called a "separated shoulder," is an injury to the ligaments that connect your collarbone (clavicle) to the top of your shoulder blade (acromion). This usually happens from a direct blow to the shoulder or a fall.
Symptoms range from mild soreness to a visible deformity, depending on the severity (Grade 1 to 6).
Top-of-Shoulder Pain: Pain is localized specifically at the very top of the shoulder.
Visible Bump: In more severe sprains, the collarbone may pop up, creating a noticeable "step" or bump.
Swelling and Bruising: Rapid onset of inflammation over the joint.
Limited Range of Motion: Difficulty lifting the arm or reaching across the body to the opposite shoulder.
Physical Exam
X-rays
Classification: Injuries are graded; Grade 1 is a mild sprain, while Grade 3 and above involve complete ligament tears and visible displacement.
Most AC joint sprains are treated without surgery, focusing on letting the ligaments tighten back up.
The "Sling" Phase: For Grades 1–3, wearing a sling for 1–3 weeks supports the weight of the arm and takes the tension off the ligaments.
Ice and Pain Management: Consistent icing in the first 48 hours is key to reducing the initial sharp pain.
Physical Therapy: Once the initial pain subsides, therapy focuses on restoring full range of motion and strengthening the deltoid and trapezius muscles to support the joint.
Surgical Reconstruction: Surgery is typically reserved for high-grade injuries (Grades 4–6) or for patients who remain painful and unstable after months of therapy.