Sternoclavicular Joint Dislocations: Anterior vs Posterior Medical Emergencies
In short
Posterior sternoclavicular dislocations compress the trachea, esophagus, and brachiocephalic vessels; immediate CT imaging and reduction prevent fatal complications.
In this guide (4 sections)
Anatomy of the Sternoclavicular Joint: The Central Skeletal Anchor
The Sternoclavicular (SC) joint is the sole true bony articulation connecting the upper extremity to the axial skeleton. It has minimal intrinsic bony stability, resembling a ball resting on a shallow saddle. Stability relies entirely on the powerful anterior and posterior sternoclavicular ligaments, the interclavicular ligament, and the costoclavicular (rhomboid) ligament.
SC joint dislocations are uncommon in general sports, accounting for under 3% of all shoulder girdle dislocations. However, they are exceedingly dangerous in rugby, rugby league, American football, equestrian sports, and motor racing. Dislocations are categorized based on the direction of displacement of the medial clavicle: anterior (common) or posterior (rare, medical emergency).
Diagnostic Differential: Anterior vs Posterior SC Dislocation
| Clinical Feature | Anterior SC Dislocation (Common) | Posterior SC Dislocation (Emergency) | Clinical Action Required | |
|---|---|---|---|---|
| Mechanism of Injury | Indirect force: compressive impact on anterolateral shoulder drives medial clavicle forward | Direct blow to medial clavicle, or posterolateral shoulder impact driving clavicle backward | Posterior vectors push medial clavicle straight into the superior mediastinum | |
| Physical Presentation | Prominent, visible subcutaneous bump beside the upper sternum | Hollow depression or indentation beside sternum; head tilted toward injured side | Posterior dislocation presents with a sunken joint, not a protrusion | |
| Life-Threatening Red Flags | None; superficial swelling and localized bone pain | Dyspnea (shortness of breath), dysphagia (difficulty swallowing), venous engorgement | Compression of trachea, esophagus, superior vena cava, or carotid artery | |
| Diagnostic Imaging | Serendipity view X-ray or CT scan | Urgent contrast-enhanced chest CT scan mandatory | CT reveals exact distance between displaced clavicle and great vessels | |
| Emergency Management | Closed reduction under sedation; often remains unstable but functionally benign | Urgent closed/open reduction in operating room with thoracic surgeon on standby | High mortality risk if vascular laceration occurs during posterior reduction |
Physiotherapy Rehabilitation Protocol
- Figure-of-Eight / Sling Immobilization (Weeks 1 to 4): Support the arm in a sling to prevent the weight of the arm from pulling down on the sternoclavicular ligaments; avoid overhead arm elevation past 90 degrees for 4 weeks.
- Pectoralis Major and Subclavius Strengthening: Begin isometric shoulder adduction and horizontal press drills at week 4; the subclavius muscle acts as a dynamic muscular sling stabilizing the medial clavicle against the first rib.
- Safe Return to Contact Drills (Months 3 to 4): Athletes recovering from anterior dislocations often retain a permanent harmless protrusion; return to contact sports is cleared once full rotational strength is verified and direct sternal palpation is pain-free.
Frequently Asked Questions
Why is a posterior sternoclavicular dislocation a medical emergency?
Behind your collarbone where it meets your chest bone lie your windpipe, your swallowing tube (esophagus), and the massive blood vessels carrying blood to your brain. If the bone dislocates backward, it can crush these vital structures, making breathing and swallowing difficult.
What should an athletic trainer do immediately on the field if a player has a posterior SC dislocation?
Immediately call emergency medical services. Place the athlete in a seated position leaning slightly forward to relieve pressure on the airway, and check their breathing, pulse in the wrist, and neck vein swelling.
Why does my chest bone click and pop when I reach across my body?
A clicking sternoclavicular joint usually indicates a mild sprain of the anterior SC ligaments or cartilage disc degeneration inside the joint. Targeted physiotherapy to strengthen your upper chest muscles typically resolves the instability.
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