The acromioclavicular (AC) joint sits where the collarbone (clavicle) meets the top of the shoulder blade (acromion), held together by a set of ligaments. An AC joint injury, often called a "shoulder separation," happens when those ligaments are stretched or torn, allowing the collarbone to shift out of its normal position.
Most commonly caused by a direct fall onto the point of the shoulder, or a direct blow — common in football, hockey, cycling, and mountain biking falls.
Pain and tenderness directly over the AC joint, swelling, and in more significant injuries, a visible bump or step-off where the collarbone sits higher than the shoulder blade. Pain is usually worse with overhead motion or reaching across the body.
Most AC joint injuries (lower-grade separations) heal well with rest, a sling for comfort, and physical therapy to restore motion and strength. Higher-grade separations, or cases with persistent pain and instability, may benefit from surgical reconstruction of the ligaments, particularly in athletes or laborers who need full overhead strength.
Think you might have this condition? An accurate diagnosis starts with an exam — schedule a consultation with Dr. Thomson.
Schedule a ConsultThis page is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Every injury is different — always consult Dr. Thomson or another qualified physician for a personalized evaluation.