Sternoclavicular separation is an uncommon sprain of the ligaments of the sternoclavicular joint (the junction between the breastbone [sternum] and the collarbone [clavicle]). When a ligament is overstretched, it becomes taut and gives way at its weakest point, either where it attaches to the bone or within its midsubstance. The sprain may range from where the collarbone keeps its normal position with respect to the sternum (nondisplaced) to the collarbone losing contact with the sternum. The collarbone may move outward (anteriorly) to become more prominent, causing a bump on the chest, or backward, behind the sternum (posteriorly).
Frequent Signs and Symptoms
- Severe pain, tenderness, swelling, and bruising and occasionally a bony bump at the sternoclavicular joint
- Pain at the sternoclavicular joint when attempting to bring the affected arm across and in front of the body
- Hoarseness of voice, difficulty swallowing, difficulty breathing, neck fullness, choking sensation (all are rare, but if any occur, these are emergency situations)
Etiology (Causes)
- Stress on a ligament by a force temporarily moving the sternoclavicular joint out of its normal position, such as with direct trauma to the collarbone near its joint with the sternum or a violent force from the side, compressing the shoulder toward the sternum
- Fall on an outstretched hand (less common)