Sternoclavicular Joint Injuries

Sternoclavicular joint injuries make up 3% of all shoulder girdle injuries. Anterior dislocations are 25 times more common than posterior ones, but it is the posterior dislocation, driven back towards the mediastinum, that makes this joint an emergency.

Who. Incidence peaks in young adults aged 15-25, injured in sport or motor vehicle accidents, with a second peak in the elderly after falls. Males are affected twice as often as females (2:1).

Anterior dislocation. An indirect force, lateral compression of the shoulder with the arm forward, displaces the medial clavicle anteriorly: it lifts up and forward. A direct blow to the anteromedial clavicle is a rare cause.

Posterior dislocation. A high-energy mechanism, such as a motor vehicle accident or a rugby tackle. A direct blow to the anterolateral clavicle, or lateral compression of the shoulder with the arm back and down, displaces the medial clavicle posteriorly into the mediastinum.

The joint. The SC joint is the only true articulation between the upper limb and the axial skeleton. It is a saddle-type synovial joint with incongruous surfaces, divided by a fibrocartilaginous intra-articular disc. The clavicle acts as a strut, transmitting forces from the upper limb to the axial skeleton, and the joint permits 35° of elevation, 35° of anterior-posterior movement and 50° of rotation.

The physis. The medial clavicular epiphysis is the last physis in the body to close, at 22-25 years. The SC ligaments are exceptionally strong, stronger than the physis, so in a patient under 25 the physis gives way first: expect a Salter-Harris I or II physeal fracture rather than a true dislocation. True dislocation requires high energy to overcome those very strong ligaments.

The stabilisers. The costoclavicular ligament, running from the first rib to the clavicle, is the primary restraint to elevation. The posterior capsule is the primary restraint to anterior and posterior translation.

What lies behind. The direction of dislocation matters because of what sits directly behind the joint.

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The physeal injury. In the under-25 patient who looks "dislocated", the epiphysis stays reduced against the manubrium, held by the intact sternoclavicular ligaments, while the metaphysis and clavicular shaft displace anteriorly or posteriorly.

Posterior displacement is still an emergency. The displaced metaphysis can compress the mediastinum just as a true posterior dislocation does, so a posteriorly displaced physeal injury is reduced urgently with the same precautions: closed reduction, cardiothoracic cover and CT angiography.

Otherwise it heals. This is a fracture through bone in a patient with enormous remodelling potential, so it heals reliably and rarely needs internal fixation. An anteriorly displaced or successfully reduced physeal injury is generally managed non-operatively, with fixation (soft-tissue, never metal) reserved for the irreducible posterior injury. That better prognosis is why distinguishing a physeal injury from a true ligamentous dislocation on CT matters.

History. Establish the mechanism: the energy involved (motor vehicle accident, sports collision, fall onto the shoulder), a direct blow or indirect lateral compression of the shoulder, and the position of the arm at the time of injury. Then ask directly about dyspnoea, dysphagia and arm swelling, the symptoms of vascular or airway compromise.

Anterior dislocation. The medial clavicle is prominent and palpable anteriorly, with swelling at the joint and pain on arm movement, especially cross-body. Full shoulder range of motion is typically preserved, and the cosmetic deformity is the main concern.

Posterior dislocation. The medial clavicle is less prominent, or the joint hollow, where the clavicle is depressed posteriorly. The findings that matter come from the structures behind it:

• Dyspnoea or stridor (tracheal compression), or respiratory distress
• Dysphagia (oesophageal compression) or odynophagia
• Venous congestion or engorgement in the neck, face or ipsilateral arm
• Diminished or absent upper limb pulses (subclavian compression)
• Hoarseness (recurrent laryngeal nerve)
• Brachial plexus symptoms or neurological deficit (rare)
• Supraclavicular haematoma

Bedside tests. Compare the radial pulses on both sides and look at the jugular and arm veins for distension. The Adson test may assess subclavian artery compression.

Plain radiographs. A standard AP film is often inconclusive because the structures overlap, and serves only as an initial screen.

The serendipity view. The classic exam view, and good for the direction of displacement. The patient lies supine and the beam is angled 40° cephalad, centred on the sternum, so that both SC joints are compared on the same film. In an anterior dislocation the affected clavicle projects above the normal side; in a posterior dislocation it projects below.

CT. The gold standard for assessing fracture and dislocation, indicated in every suspected dislocation. It is definitive for the direction of displacement and identifies associated fractures, and with contrast it assesses vascular compression or injury.

MRI. Shows the soft tissues and the physeal injury in young patients, and is used in subacute and chronic cases.

Every injury is first assessed for a posterior dislocation or mediastinal symptoms; the rest of the algorithm follows from that answer.

Algorithm

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Indications. Reconstruction is for chronic symptomatic instability, anterior or posterior, that affects function after failed conservative management, including recurrent dislocation affecting function.

Hardware migration. Multiple case reports document fatal migration of pins, screws and plates from the SC joint into the heart (cardiac tamponade), the aorta (haemorrhage), the pulmonary vessels and the subclavian vessels. Migration can occur months to years after surgery.

Managing complications. A vascular injury needs immediate thoracic or vascular surgery. Chronic instability is treated with figure-of-8 reconstruction, and arthritis, rarely, with medial clavicle resection.

After closed reduction. CT confirms the reduction and serial radiographs confirm that it is maintained. A figure-of-8 brace or sling is worn for 6 weeks, because strict immobilisation is required for soft-tissue healing, with NSAIDs for pain and ice to reduce swelling, followed by progressive range of motion. Serial neurovascular examinations continue, watching for delayed vascular complications.

After figure-of-8 reconstruction. The protocol runs from sling protection to functional testing before return to sport.

Natural history. Most SC injuries have excellent outcomes with conservative treatment, and even with residual deformity function is typically normal. Posterior dislocations require intervention, but outcomes are good if they are treated promptly.

The percentages above are illustrative conventional estimates from the case-series literature, not measurements from a single cohort; the sourced anchors are Groh 2011 (18 of 21 good or excellent after posterior dislocation treatment) and Kendal 2018 (favourable outcomes across all five stabilisation categories, 16% overall complications).

Prognostic factors. These influence the outcome:

• Time to treatment, especially in posterior dislocation
• Age (younger patients do better)
• Associated injuries
• Compliance with rehabilitation

Global Epidemiology:

Guidance Across Major Bodies:

There is no dedicated AAOS, NICE or BOAST guideline specific to SC joint dislocation; this is a rare injury where practice is driven by case series, systematic reviews and trauma-system principles rather than formal society guidelines. The consensus positions below are drawn from the indexed evidence base.

Registry and Practice Variation:

• No national joint registry (NJR, AJRR, AOANJRR, SHAR) captures SC joint dislocation as a tracked procedure, reflecting its rarity and the absence of an implanted prosthesis; the best population-level data come from national administrative datasets such as the German big-data analysis above.
• Practice variation is driven chiefly by access to cross-sectional imaging and cardiothoracic surgery rather than by regional guideline differences: in well-resourced settings CT angiography and on-site thoracic cover are standard before reducing a posterior dislocation, whereas in limited-resource settings prompt closed reduction may proceed with whatever surgical backup is available, accepting higher risk.
• The single global constant across all settings is the absolute avoidance of trans-articular metalwork.