Description

• Sternoclavicular joint (SCJ) is the only joint that connects the upper limb to the trunk
• Among the least frequently injured joints in the body
• Most commonly due to athletic or vehicular injuries
• Congenital or spontaneous dislocation and subluxation are rarely seen
• SCJ stability depends on ligamentous attachments, primarily anterior and posterior sternoclavicular ligaments, interclavicular ligament, and costoclavicular ligament
• Diagnosis of injury or dislocation requires a high suspicion

Etiology

• Injury to the SCJ can be from sprains, subluxations, or dislocations of the ligamentous structure
• In sprains, ligamentous capsule remains intact
• Subluxation occurs when sternoclavicular ligament ruptures while costoclavicular ligament remains intact
• Complete ligamentous disruption leads to dislocation
• The SCJ can dislocate anteriorly or posteriorly. A large force is required. A greater force is required to displace the clavicle posteriorly
• Dislocations may be more common in patients with hypermobility syndromes such as Ehlers–Danlos syndrome
• Direction of dislocation depends on the shoulder position:
  • Anterior dislocation more likely when the acromion is posterior to the manubrium
  • Posterior dislocation more likely when the acromion is anterior to the manubrium
• Anterior dislocation is more common (more than 90% of dislocations):
  • Caused by a posteriorly directed force to the anterolateral aspect of the shoulder
  • Reciprocal anterior displacement of the medial clavicle
  • May be associated with pneumothorax, hemothorax, pulmonary contusion, or rib fractures
  • Subluxation and dislocation may occur spontaneously
• Posterior SCJ dislocation results from:
  • Anterior-to-posterior blow to the medial clavicle
  • Anteriorly directed force to the lateral aspect of the ipsilateral shoulder
  • A blow to the contralateral shoulder when the injured side is braced against an immobile object
• Posterior dislocation is a surgical emergency:
  • Indications for immediate reduction:
    • Compression or tear of trachea, esophagus, or great vessels
    • Recurrent laryngeal nerve injury

• The medial epiphyseal growth plates of the clavicles are last to ossify, and fuse between ages 22 and 25:
  • Until fusion, growth plate is the weakest part of the joint
• Fractures through the medial epiphysis mimic SCJ dislocations:
  • Most commonly Salter–Harris type I or II fractures
  • True dislocations of the SCJ are extremely rare in children because of strong ligamentous attachments