The sternoclavicular joint is the most frequently mobilized non-axial, major joint, but is the least frequently dislocated. Most sternoclavicular dislocations are anterior. When posterior sternoclavicular joint dislocations do occur, they may present with a variety of signs and symptoms, including serious intrathoracic injuries. We discuss the case of a patient with a subacute posterior sternoclavicular dislocation who presented to the emergency department 2 months after being hit in the posterior neck. We also review the signs, symptoms and management of posterior sternoclavicular dislocation and the literature on this topic.