We report a case of atraumatic spontaneous posterior subluxation of the ste
rnoclavicular joint in a 19-year-old woman without any known underlying pat
hology. There was no history of injury. The patient was treated operatively
using the gracilis tendon to reinforce the anterior sternoclavicular ligam
ent. One year later the patient is asymptomatic and has returned to her usu
al life.