Introduction Diarthrodial saddle joint incongruous (~50% contact) fibrocartilage (not synovial cartilage) contains an intra-articular disc Motion elevation of arm to 90° leads to rotation of the sternoclavicular joint of 30° Imaging best assessed radiographically by Serendipity view involves 40° cephalic tilt view of sternum and clavicle CT scan is most sensitive and specific Stabilizing Ligaments of Sternoclavicular Joint Posterior sternoclavicular capsular ligament primary restraint for anterior-posterior stability Anterior sternoclavicular ligament primary restraint to superior displacement of medial clavicle Costoclavicular (rhomboid) ligament anterior fasciculus resists superior rotation and lateral displacement posterior fasciculus resists inferior rotation and medial displacement Intra-articular disk ligament prevents medial displacement of clavicle secondary restraint to superior clavicle displacement Medial Clavicle Anatomy Clavicle is the first bone to begin the ossification process ossifies between 5th and 6th weeks of gestation Clavicle is the last bone to complete the ossification process medial epiphysis of clavicle is last physis to close at 20-25 yrs Important to distinguish SC dislocations from physeal fractures most injuries at this location involve the medial clavicular physis before age of 25