This article, titled "Swellings of the sternoclavicular joint: review of traumatic and non-traumatic pathologies," published in EFORT Open Reviews (2018), provides a comprehensive overview of the Sternoclavicular Joint (SCJ)—often called the "forgotten joint."

https://eor.bioscientifica.com/view/journals/eor/3/8/2058-5241.3.170078.xml

The review is structured to help clinicians navigate the rarity of SCJ conditions, which often lead to delayed diagnosis. Below is a logical summary of the key findings.

1. Anatomy and Biomechanics

The SCJ is the only bony attachment between the upper limb and the axial skeleton (the torso).

  • Stability: It is inherently unstable because less than 50% of the medial clavicle's surface area actually articulates with the sternum. Stability relies heavily on the posterior capsule (the strongest ligamentous constraint) and the costoclavicular ligaments.
  • Movement: It allows for significant mobility, including rotation (up to 45°) and shrugging/protraction.
  • Proximity Risks: Its location is clinically critical due to the proximity of the trachea, esophagus, and major neurovascular structures (like the subclavian vessels) located just behind the joint.

2. Traumatic Pathologies

Traumatic injuries account for only about 3% of all shoulder girdle injuries.

  • Mechanism: Typically caused by high-energy impacts, such as motor vehicle accidents or sports.
  • Classification:
    • Anterior Dislocation: Most common (3:1 ratio). Usually managed conservatively as it poses less risk to internal structures.
    • Posterior Dislocation: A medical emergency. The medial clavicle is pushed backward, potentially compressing the airway or major vessels.
  • Management:
    • Acute cases: Closed reduction (under sedation) is attempted first.
    • Persistent instability: May require surgical stabilization using grafts or internal fixation.

3. Non-Traumatic Pathologies

The article categorizes non-traumatic swellings into several clinical groups:

Degenerative & Inflammatory

  • Osteoarthritis: Common in older patients or manual laborers. Usually presents as a slow-growing, mildly painful swelling.
  • Condry-medial Clavicle Hyperostosis: Excessive bone growth often seen in post-menopausal women.
  • Rheumatoid Arthritis: Can affect the SCJ, leading to joint erosion and instability.

Infectious (Septic Arthritis)

  • A rare but serious condition. It often presents with sudden onset of pain, fever, and redness.
  • Risk Factors: IV drug use, diabetes, or central venous catheters. It requires urgent drainage and long-term antibiotics.

Uncommon Syndromes

  • SAPHO Syndrome: (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis). A rare inflammatory disorder where SCJ involvement is a hallmark feature.
  • Friedrich’s Disease: Avascular necrosis (death of bone tissue) of the medial end of the clavicle, usually in adolescents.
  • Tietze Syndrome: Painful swelling of the costochondral junctions, often involving the SCJ.

4. Diagnostic Algorithm

Because many SCJ conditions look similar (a "lump at the base of the neck"), the article suggests a systematic approach:

  1. Clinical History: Distinguish between acute trauma vs. chronic onset.
  2. Physical Exam: Assess for signs of airway or vascular compromise (critical in posterior dislocations).
  3. Imaging: X-rays:* Often difficult to interpret due to bone overlap (Serendipity view is recommended).
    • CT Scan: The gold standard for assessing bony anatomy and posterior displacement.
    • MRI: Best for assessing soft tissue, infection, and inflammatory conditions like SAPHO.

5. Clinical Conclusion

The authors emphasize that while SCJ swellings are rare, they require a high index of suspicion. Anterior swellings are often benign or degenerative, whereas posterior displacements or infectious signs require immediate, aggressive intervention to prevent life-threatening complications.