Sternoclavicular Injuries

Sternoclavicular (SC) joint injuries are uncommon, accounting for less than 3% of shoulder girdle injuries, but are potentially life-threatening when posterior dislocation compresses mediastinal structures. The SC joint is the only true synovial articulation between the upper limb and the axial skeleton. Its stability relies almost entirely on ligamentous constraints rather than bony congruity.

• The SC joint has the least bony stability of any major joint — articular surface contact is minimal; the medial clavicle is larger than the clavicular notch of the sternum
• Stabilising ligaments: anterior and posterior sternoclavicular ligaments (primary restraints to anterior and posterior translation), costoclavicular ligament (rhomboid ligament — limits elevation and protraction), and interclavicular ligament
• The posterior SC ligament is the strongest and most important restraint — its disruption allows posterior dislocation
• Intra-articular disc (meniscus homologue) is present — absorbs compressive forces; frequently torn in injury
• Posterior relations of the SC joint: brachiocephalic vein, subclavian artery and vein, common carotid artery, trachea, oesophagus, superior vena cava — all at risk with posterior dislocation
• Medial clavicular physis: last physis in the body to close — closes at age 23–25 years; in patients under 25, apparent SC dislocation is often a physeal fracture (Salter-Harris I or II through medial clavicular physis)

• Anterior dislocation (75%): direct blow or indirect force rolling shoulder anteriorly; medial clavicle prominent anteriorly
• Posterior dislocation (25%): medial clavicle displaced into mediastinum — can compress trachea, oesophagus, great vessels; presents with dyspnoea, dysphagia, venous congestion, hoarseness, or vascular compromise

• Clinical exam: SC joint swelling, tenderness, deformity; anterior prominence (anterior dislocation) vs medial hollowing (posterior dislocation); assess airway, voice, swallowing, and upper limb vascular status in posterior dislocation
• Plain radiographs: standard views are often inadequate — SC joint difficult to visualise on AP chest; serendipity view (40° cephalic tilt AP): anterior dislocation = medial clavicle projects superiorly; posterior dislocation = medial clavicle projects inferiorly relative to normal side
• CT scan: investigation of choice — defines direction of dislocation, mediastinal compression, vascular injury, and physeal fracture vs true dislocation; mandatory before any reduction attempt in posterior dislocation
• CT angiography: if vascular injury suspected — subclavian or carotid injury can occur with posterior dislocation
• In patients under 25 years: CT will often show physeal fracture rather than true ligamentous dislocation — the periosteum remains attached and the epiphysis stays in joint; management principles the same

Anterior Dislocation:

• Attempt closed reduction in acute setting: arm traction in extension with scapular retraction; direct anterior pressure on medial clavicle
• Reduction often achieved but unstable — re-dislocates anteriorly in most cases
• Anterior dislocation: accept residual anterior prominence if reduction unstable — functional outcomes are generally good without perfect reduction; operative stabilisation rarely needed acutely
• Sling for 4–6 weeks; physiotherapy; most patients achieve satisfactory function
• Chronic symptomatic anterior instability: medial clavicle resection or ligament reconstruction (figure-of-eight tendon graft through manubrium and medial clavicle)

Posterior Dislocation — Emergency Management:

• Posterior SC dislocation = orthopaedic emergency — cardiothoracic surgery must be on standby before any reduction attempt; vascular injury can be unmasked by reduction
• Closed reduction technique: patient supine with sandbag or bolster between scapulae; traction-abduction of arm with shoulder extended; direct anterior traction on medial clavicle with towel clip if needed
• Stable reduction after closed reduction: immobilise in figure-of-eight harness for 4–6 weeks
• Irreducible posterior dislocation or vascular compromise: open reduction — deltopectoral or anterior cervical approach; take great care with posterior structures; have cardiothoracic surgeon present
• If mediastinal structures injured: urgent vascular or cardiothoracic surgery before orthopaedic reduction

Chronic Instability:

• Chronic anterior instability: figure-of-eight ligament reconstruction (semitendinosus or gracilis graft) — good results; avoid K-wire fixation across SC joint (catastrophic complication if wire migrates)
• Medial clavicle resection: for osteoarthritis or chronic instability — must preserve costoclavicular ligament attachment to prevent medial clavicle instability after resection
• K-wire fixation of SC joint is absolutely contraindicated — multiple reported deaths from wire migration into heart and great vessels

• Physeal fracture vs true dislocation in young patients: CT differentiates — in physeal injury, the epiphysis remains in the joint and the periosteum is intact on one side; reduction and healing are more reliable in physeal injuries; the physis remodels reliably under age 25
• Posterior dislocation masquerades as a benign injury on physical examination — clinical suspicion is everything; do not attempt reduction without CT confirmation of direction and without cardiothoracic backup
• Ligament reconstruction technique: figure-of-eight graft through drill holes in the manubrium and medial clavicle — graft must be tensioned carefully; overtightening restricts clavicular motion; undertightening fails; subclavius tendon can also be used
• Medial clavicle resection for OA: remove 10–15 mm of medial clavicle; must preserve the costoclavicular ligament (resect medial to its attachment at the rhomboid fossa); failure to preserve the costoclavicular ligament leads to iatrogenic instability
• Spontaneous SC joint infections: occur in IV drug users and immunocompromised patients — present with SC joint pain, swelling, and fever; diagnose with MRI and aspiration; treat with antibiotics and surgical debridement if abscess or osteomyelitis present

• Medial clavicular physis closes last — at age 23–25; apparent SC dislocation in patients under 25 = physeal fracture until proven otherwise
• Posterior SC ligament = strongest SC ligament = primary restraint to posterior dislocation
• Posterior dislocation = emergency — trachea, oesophagus, great vessels at risk; cardiothoracic standby mandatory before reduction
• Serendipity view (40° cephalic tilt): anterior dislocation = clavicle rides superiorly; posterior = clavicle depressed relative to contralateral side
• CT scan mandatory — confirms direction, assesses mediastinal structures, differentiates physeal fracture from true dislocation
• K-wire fixation across SC joint = absolutely contraindicated — fatal wire migration reported
• Anterior dislocation: accept prominence if unstable after reduction — functional outcomes good without perfect reduction
• Chronic SC instability reconstruction: figure-of-eight tendon graft through manubrium and medial clavicle
• Medial clavicle resection: preserve costoclavicular ligament or iatrogenic instability results
• SC joint infections: IV drug users, immunocompromised — MRI and aspiration; surgical debridement if abscess