Scapula Fractures: Causes, Diagnosis and Treatment
Summary
Scapula Fractures are uncommon fractures to the shoulder girdle caused by high energy trauma and associated with pulmonary injury, head injury, and increased injury severity scores. Diagnosis can be made with plain radiographs and CT studies are helpful for fracture characterization and surgical planning. Treatment is usually nonoperative with a sling. Surgical management is indicated for intra-articular fractures, displaced scapular body/neck fractures, open fractures, and those associated with glenohumeral instability.
Epidemiology
What is the incidence rate for scapula fractures?
What is the most common location for scapula fractures?
Causes of Scapula Fractures
What is the most common mechanism of injury for scapula fractures?
What percentage of scapula fractures are associated with orthopaedic injuries?
Diagnosis
What imaging studies are helpful for fracture characterization and surgical planning?
What is the recommended approach for diagnosing scapula fractures?
Treatment
What is the usual treatment for scapula fractures?
When is surgical management indicated for scapula fractures?
Scapula Fracture Epidemiology
Incidence
- Rare - less than 1% of all fractures
- 3-5% of shoulder girdle fractures
Demographics
- Age - commonly between 25-50
- Males > females
Location
- Scapular body/spine - 45-50%
- Glenoid - 35%
- Glenoid neck - 25%
- Glenoid fossa/rim - 10%
- Often associated with impaction of humeral head into glenoid
- Acromion - 8%
- Coracoid - 7%
Scapula Fracture Etiology
Pathophysiology
- Mechanism of injury
- High-energy trauma (80-90%)
- Motor vehicle collisions account for >70% of scapula fractures
- Indirect trauma through fall on outstretched hand
- Glenohumeral dislocation
- Anterior dislocation leads to anterior rim fracture
- Posterior dislocation leads to posterior rim fracture
- Seizure
- Electric shock
- Associated injuries (in 80-95%)
- Medical
- Thoracic injury (80%)
- Hemothorax/pneumothorax (>30%)
- Pulmonary contusion (>40%)
- Head injury (35-50%)
- Orthopaedic
- Rib fractures (53%)
- Ipsilateral extremity injury (50%)
- Ipsilateral clavicle fractures (25%)
- Spine fracture (26-30%)
- Pelvic ring/acetabular fractures (15%)
- Scapula fracture is important predictor of:
- Upper extremity vascular injury (11%)
- Subclavian and axillary arteries at risk
- Higher risk with scapulothoracic dissociation
- Brachial plexus injury (5-13%)
- 75% of brachial plexus injuries resolve
- Complete brachial plexus injuries less likely to resolve
Scapula Fracture Anatomy
Osteology
- Scapular body
- Origin or insertion of 18 muscles
- Function to connect scapula to thorax, spine and upper extremity
- Large triangle shape with 4 major processes
- Scapular spine
- Osseous bridge separating supraspinatus and infraspinatus
- Spinoglenoid notch represents possible site of compression for suprascapular nerve
- Glenoid
- Represents articulating process on lateral scapula serving as socket for glenohumeral joint
- Pear-shaped and wider inferiorly from anterior to posterior
- Average 1-5º of retroversion and 15º superior tilt from scapular plane
- Fibrocartilaginous labrum deepens glenoid fossa by 50% to increase stability
- Acromion
- Articulates with clavicle to form acromioclavicular joint
- Formed by 3 ossification centers
- Pre-acromion - tip
- Meso-acromion - mid
- Meta-acromion - base
- Coracoid process
- Has two secondary ossification centers that are open until around age 25 and should not be interpreted as fracture
- Angle of coracoid
- Tip of coracoid
- Muscular attachments
- Conjoint tendon
- Coracobrachialis
- Short head biceps
- Pectoralis minor
- Ligament attachments
- Coracoclavicular (CC) ligaments
- Most anterior CC ligament attachment is 25mm from tip of coracoid
- Coracoacromial ligament
Arthrology
- Glenohumeral joint
- Glenoid & labrum support humeral head to produce high degree of motion
- Stability provided by static and dynamic stabilizers
- Scapulothoracic joint
- Not a true joint but does represent an articulation between scapula and thorax
- Involved primarily in elevation and depression of shoulder as well as rotation and pro-/retraction
- Acromioclavicular (AC) joint
- Articulation of acromion and distal clavicle
- Supported by acromioclavicular ligaments (horizontal stability) and coracoclavicular ligaments (vertical stability)
- 8º of rotation occurs through acromioclavicular joint
- Superior shoulder suspensory complex
- Bone & soft tissue ring which provides connection of glenoid/scapula to axial skeleton
- Composed of 4 bony landmarks
- Distal clavicle
- Acromion
- Coracoid
- Glenoid
- Also composed of ligamentous complexes of acromioclavicular and coracoclavicular joints
Blood supply
- Contributions from anterior and posterior circumflex, scapular circumflex and suprascapular arteries
- Watershed area present in anterosuperior glenoid
Nervous system
- Scapula is intimately associated with brachial plexus
- Axillary nerve is at risk inferior to the glenoid as it runs from anterior to posterior
- Compression of suprascapular nerve at scapular notch leads to supraspinatus/infraspinatus weakness, with compression at the spinoglenoid notch leading only to infraspinatus weakness
Biomechanics
- Scapula contributes to glenohumeral rotation and abduction
- 1/3 of shoulder motion is scapulothoracic, 2/3 is glenohumeral
Scapula Fracture Classification
Classification is based on the location of the fracture and includes
- Scapular body fractures
- Usually described based on anatomic location
- Scapular neck fractures
- Look for associated AC joint separation or clavicle fracture
- If occurring together, known as "floating shoulder"
- Glenoid fractures
- Ideberg classification with Goss modification (below)
- Low inter- and intra-observer reliability and questionable association with management
- AO-OTA classification
- More reliable in diagnosis than Ideberg classification
- Acromial fractures
- Kuhn classification
- Coracoid fractures
- Ogawa classification - based on fracture proximity to CC ligaments
- Eyres classification
- Scapulothoracic dissociation
- Ogawa Coracoid Fracture Classification
- Type I - fracture occurs proximal to the coracoclavicular ligament
- Type II - fracture occurs towards the tip of the coracoid
Scapula Fracture Presentation
History
- Traumatic direct blow to shoulder or fall on outstretched arm
- Scapula fracture may be missed or diagnosed late in presence of other distracting, traumatic injuries
Symptoms
- Diffuse, severe shoulder pain
- Systemic symptoms
- Shortness of breath
- Chest wall pain
Physical exam
- Inspection
- Tenderness to palpation
- Shoulder diffusely
- Inaccurate in determining specific location of fracture
- Clavicle
- Spine
- Rib cage
- Evaluate for abnormal shoulder contour compared to contralateral site
- Look for open wounds or abrasions
- Soft tissue swelling may be significant
- Motion
- Acute active range of motion testing not recommended
- Likely to cause unnecessary pain
- Gentle passive range of motion can be useful in noting any blocks to motion
- Neurovascular
- Check motor and sensory function of nerves at risk
- Axillary
- Radial
- Median
- Ulnar
- Confirm symmetry of extremity pulses to contralateral side
Scapula Fracture Imaging
Radiographs
- Recommended views
- True AP, Grashey AP, scapular Y, and axillary lateral view
- AP chest radiograph
- Evaluate for pneumothorax
- Evaluate for widening of space between medial scapular border and spine
- >1 cm indicates possible scapulothoracic dissociation
- Measurements
- Intra-articular step-off
- Lateral border offset (medialization)
- Glenopolar angle (measured on Grashey AP)
- Angle connecting superior/inferior scapula and lateral border of scapula
- Normal considered 30-45º
- Scapular angulation
- Best seen on scapular Y radiograph
CT
- Indications
- Intra-articular fracture
- Significant displacement >1cm
- May also help detect other thoracic/spine injuries
- Views
- Three-dimensional reconstruction better demonstrates fracture patterns
- Coronal and axial views useful to evaluate displacement, intra-articular step-off and medialization of glenoid
- Sagittal view useful to evaluate anterior-posterior displacement and angulation
MRI
- Indications
- Not regularly obtained but may be useful in some cases to evaluate the superior shoulder suspensory complex for ligamentous injury
Scapula Fracture Differential
Os Acromiale
- Unfused secondary ossification centers (meso- and meta-acromion)
- Associated with impingement and rotator cuff symptoms and may be detected incidentally with trauma
Scapula Fracture Treatment
Nonoperative
- Sling for 2-3 weeks, followed by early motion
- Scapular body fractures
- Indications:
- Indicated for vast majority of scapula fractures
- 90% are minimally displaced and acceptably aligned
- Outcomes:
- Progressive deformity/displacement is possible during first 3 weeks
- Recommend serial weekly radiographs during this time
- Those associated with multiple underlying rib fractures or superior shoulder suspensory complex disruptions are more likely to displace
- Union at 6-8 weeks in most cases
- Most recover near-normal function
- Attributed to shoulder's capability for compensatory motion
- Poorer outcomes noted in patients with glenopolar angle <20º
- Scapular neck fractures
- Indications:
- Translation <1 cm
- Angulation <40º
- Glenopolar angle >20º
- No additional injury to superior shoulder suspensory complex
- Outcomes:
- True outcomes not well established
- Some reports of unsatisfactory results