Scapula Fractures

Scapula fractures are uncommon injuries that typically result from high-energy trauma. The scapula is protected by thick muscle coverage, and significant force is required to fracture it.

Mechanism. Motor vehicle accidents are the most common cause, at 50-70%. Falls from height and direct blows (crush injuries) account for others. Sport causes them uncommonly, and then typically with low energy.

A marker of energy. A scapula fracture indicates massive energy transfer, and the fracture itself is often less important than the injuries that came with it. Maintain a high suspicion for associated injuries and always perform a thorough trauma assessment.

How treatment has shifted. Traditionally, scapula fractures were treated almost universally conservatively, with good results. The shift to surgical treatment in selected cases is based on a better understanding of outcomes with significantly displaced glenoid neck and articular fractures.

The bone. The body is a flat triangular bone, thin at 2-7mm. The named parts:

• Spine - posterior ridge that divides supraspinatus from infraspinatus
• Acromion - lateral extension of the spine, articulating with the clavicle
• Coracoid process - anterior projection carrying muscle and ligament attachments
• Glenoid fossa - articular surface for the humeral head
• Glenoid neck - transition between glenoid and body

The superior shoulder suspensory complex (SSSC). A bone-ligament ring that suspends the upper extremity from the axial skeleton. Its components are the glenoid process, coracoid, coracoclavicular (CC) ligaments, distal clavicle, AC joint and acromion, with the scapular spine forming the ring superiorly. The clavicle is its superior strut, the link to the axial skeleton. A single disruption is stable; a double disruption is the floating shoulder, a potential instability that is judged on residual glenoid displacement.

Muscles. Seventeen muscles attach to the scapula, including:

• Rotator cuff - supraspinatus, infraspinatus, teres minor, subscapularis
• Scapulohumeral - deltoid (partial), coracobrachialis, biceps (long head)
• Axioscapular - trapezius, levator scapulae, rhomboids, serratus anterior
• Scapulothoracic - pectoralis minor, omohyoid

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Neurovascular relationships. The structures at risk:

• Suprascapular nerve - in the suprascapular notch; injury in coracoid fractures
• Axillary nerve - quadrangular space
• Subscapular nerves and vessels
• Brachial plexus - runs anterior to the scapula

Where the fracture lies. The anatomic classification is the most practical, and location carries the prognosis. Glenoid fractures are the most important prognostically because they affect glenohumeral joint function. Glenoid neck fractures matter when significantly displaced or combined with a clavicle injury (the floating shoulder). Body fractures are treated conservatively, the thick muscle coverage aiding healing.

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Coracoid fractures: the Ogawa classification. The coracoid fracture is classified by its relation to the coracoclavicular (CC) ligament attachment, which decides whether the SSSC ring is still intact.

• Type I - posterior (proximal) to the CC ligament attachment. The fracture lies behind the conoid and trapezoid insertions, so the CC ligaments stay attached to the distal fragment and the coracoid strut is detached from the clavicle and SSSC linkage. It behaves like a double disruption, often with an associated AC joint separation or distal clavicle fracture, and it is unstable: this is the type that often needs ORIF.
• Type II - anterior (distal) to the CC ligament attachment, at the coracoid tip. The CC ligaments still bridge clavicle to scapula and the ring is intact, so this is a stable avulsion, usually treated non-operatively.

Suspect a Type I double lesion whenever a coracoid fracture coexists with an AC joint disruption; that is why displacement and an associated AC injury push toward fixation. CT is particularly useful when an apparently isolated coracoid fracture may be part of a double disruption of the SSSC.

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History. The questions that shape the assessment:

• Mechanism - MVA, fall from height, direct blow
• Associated symptoms - chest pain, dyspnoea, neurological symptoms
• Pre-injury function
• Hand dominance

Associated injuries. Between 80 and 95% of patients have them, and rib fractures are the most common association:

• Rib fractures - 52%
• Pulmonary contusion - 47%
• Pneumothorax - 38%
• Clavicle fractures - 23%; with a neck fracture, the floating shoulder
• Brachial plexus injury - 12%
• Humeral fractures - 11%
• Spine fractures (cervical and thoracic) - 8%
• Acromioclavicular injury - may be concomitant
• Subclavian artery injury - rare but serious; vascular injury in severe cases

Scapulothoracic dissociation. Look at the chest X-ray for lateral displacement of the scapula compared with the contralateral side. It indicates complete disruption of the scapulothoracic attachments with massive soft-tissue trauma, a high likelihood of subclavian or axillary artery injury, and brachial plexus avulsion. Mortality is high, and forequarter amputation may be required.

The scapula index puts a number on the displacement: the normal average is 1.07, and dissociation is suspected if the ratio exceeds 1.29.

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A vascular emergency. A laterally displaced shoulder girdle with a cool, pulseless or neurologically flail limb is a vascular emergency. Document perfusion and brachial plexus function, then obtain urgent vascular imaging without delaying resuscitation.

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Trauma series first. The AP chest, AP pelvis and lateral C-spine series comes first, and the chest X-ray is often the first film to show the scapula fracture. Read it for lateral scapular displacement (scapulothoracic dissociation), rib fractures and pneumothorax.

Dedicated scapula views. Three projections:

• True AP scapula (Grashey view) - 30-40 degree posterior oblique
• Scapula Y-view (lateral) - shows the glenoid neck and body; as a true lateral it complements the AP and axillary projections by showing sagittal angulation and the relationship of the glenoid to the scapular body
• Axillary lateral - glenoid rim fractures

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The glenopolar angle (GPA). Measured on the true AP or Y-view, it describes glenoid alignment relative to the scapular body. One line joins the most superior and inferior points of the glenoid; a second runs from the superior glenoid to the inferior angle of the scapula. Normal is 30-45 degrees, and 22 degrees or less indicates significant displacement and is the commonly quoted operative threshold. Interpret it with displacement and clinical context rather than in isolation.

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CT. Thin-slice CT with multiplanar reformats and three-dimensional reconstruction characterises body, neck and articular extension, quantifies glenoid step and gap, and reveals fracture components that are frequently occult on plain radiographs. It is essential for:

• All glenoid fractures - articular surface assessment
• Surgical planning for displaced neck fractures
• Complex or comminuted patterns
• Assessment of lateral border offset

The 3D reconstruction is excellent for visualising the fracture pattern and helps plan the surgical approach and fixation strategy.

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CT angiography. Indicated for:

• Scapulothoracic dissociation
• Expanding haematoma
• Absent or diminished pulses
• Suspected subclavian or axillary injury

Most are treated without surgery. The majority of scapula fractures, 80-90%, are treated conservatively with good outcomes.

The decision by pattern. Surgery depends on the fracture's location and how far it has displaced.

The glenoid fossa. Articular step, fragment size and instability affect long-term shoulder function, and the Ideberg classification guides treatment.

The neck thresholds are conventions, and you should say so. They are consensus operative indications proposed from expert practice and small retrospective series. No randomised or prospective comparative study has validated any of them, and no trial has shown that operating on a scapula that crosses a cut-off produces a better result than one that does not.

• The glenopolar angle is measured on a true AP that is often imperfect in a polytrauma patient and is sensitive to scapular rotation, so a borderline value should be re-measured on CT rather than acted on
• Medialisation and angulation are read differently on plain films and on 3D CT, with CT generally showing more displacement

Use them to structure the discussion and to justify referral, not as a switch that decides the operation on its own.

The floating shoulder. Decide from displacement, glenoid alignment, ligamentous integrity, associated injuries and residual instability after clavicular reduction, not from the label. When fixation is chosen, stabilise at least one limb of the ring, usually the clavicle first: it is technically easier to reach and often provides sufficient stability. If residual scapular displacement persists after clavicle fixation, address the scapula neck. Some advocate fixing both primarily, but the evidence suggests clavicle fixation is often sufficient.

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Approach selection depends on the fracture pattern and the associated injuries.

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Stiffness is the most common complication. It is related to prolonged immobilisation and associated injuries, and the prevention is early motion when it is safe.

Post-traumatic arthritis occurs primarily after glenoid fossa fractures and is related to residual step-off, which is what makes anatomic reduction of articular fractures important.

Protection and early motion. The post-ORIF protocol balances protection of the repair against early motion, and rotator cuff function is critical for the outcome. Serial imaging should confirm that fixation remains stable while rehabilitation advances from protected passive motion to active motion and strengthening, according to fracture union and soft-tissue repair.

The whole patient. Build the associated injuries (rib, clavicle) into the rehabilitation plan, and educate the patient about the expected timeline.

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What decides the result. The associated injuries (head, chest) are the major determinant of mortality, and the quality of articular reduction the major determinant of shoulder function. Patient age, bone quality and rehabilitation compliance also bear on it.

Global epidemiology

Scapula fractures are uncommon worldwide and almost always a marker of high-energy transfer; injury patterns therefore track regional trauma epidemiology (road-traffic and motorcycle trauma in much of Asia, Africa and Latin America; falls and vehicle crashes in higher-income settings).

Guidance, side by side

There is no single dedicated international guideline for scapula fractures; management is anchored on the AO Foundation principles plus society trauma-system standards. Recommendations are largely concordant because the evidence base is uniformly low (level IV).

Registry evidence

Scapula fractures are not implant-survival procedures, so the major arthroplasty registries (NJR, AJRR, AOANJRR, SHAR, Norwegian, NZJR) do not track them directly. Epidemiology instead comes from national trauma databases: a US National Trauma Data Bank analysis of 9,453 scapular fractures (Baldwin et al., J Trauma 2008) showed that, after adjusting for injury severity, upper-extremity, thoracic and pelvic-ring injuries remained significantly associated with scapula fracture, while many other "associations" reflected overall injury severity rather than the scapula fracture itself.

Global practice variation

• High-resource settings: ready CT and 3D reconstruction, sub-specialist shoulder/trauma surgeons, and trauma-network transfer make selective ORIF (Judet or single lateral-column approach) routine for displaced patterns.
• Limited-resource settings: CT may be scarce and most fractures are managed non-operatively with sling and early motion, which is supported by the evidence for the majority of body and minimally displaced neck fractures.
• Scapulothoracic dissociation is a universal surgical emergency requiring immediate vascular assessment regardless of setting; outcomes depend on access to vascular surgery and ICU support.