Bony Thorax Case 2 Background

The sternoclavicular (SC) joint is a stable saddle joint connecting the upper extremity to the axial skeleton. Due to its strong ligamentous attachments, SC joint dislocations are quite rare (<1% of all joint dislocations and <3% of all shoulder girdle dislocations). SC joint dislocations are typically caused by high impact injuries, such as motor vehicle accidents and contact sports.

Anterior SC joint dislocation is nine times more common than posterior due to the increased strength of the posterior ligament. Posterior dislocation is much more dangerous due to the mediastinal structures in close proximity (subclavian vessels, lungs, carotid arteries, trachea, esophagus, etc). In fact, 30% of posterior dislocations are associated with a life-threatening complication due to mediastinal injury, with mortality estimated at 3-4%.