scapulothoracic dissociation
A 38-year-old, left-hand-dominant male was brought to the ED after a high-speed MVC. He sustained a closed injury but is alert and able to participate fully in his physical examination. He has a couple of broken ribs and is being monitored, and complains of left shoulder pain. His radiographs and CT scan is shown in Figure 6–4A–E.
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Figure 6–4 A–E
Which statement is true regarding scapula fractures?
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They are common and are a result of low-energy trauma.
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There is an 80% rate of associated injuries.
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The most common associated injury is to the head.
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Associated brachial plexus injuries leave permanent disability 50% of the time.
Discussion
The correct answer is (B). Scapula fractures are uncommon (<1% all fractures) and are typically a result of a high-energy mechanism. There is a 2% to 5% mortality
rate. The most common associated injury is rib fractures, with over 50% incidence. Head injuries occur 34% of the time. Other associated injuries include clavicle fracture, spine fractures, pneumothorax, pulmonary contusions, and vascular injury. Brachial plexus injuries occur in 5% of scapula fractures, and 75% of them resolve over time.
Which of the following would NOT be an indication for surgery?
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Coracoid fracture with 4 mm displacement.
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Scapula neck fracture with 12 mm of translation.
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Ipsilateral middle-third clavicle fracture with <100% displacement.
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Glenoid medialization.
Discussion
The correct answer is (A). Surgical Indications for scapula fractures includes: open fractures, loss of rotator cuff function, a coracoid fracture with more than 10 mm displacement, a neck fracture with either 40 degrees angulation or 10 mm displacement, or glenohumeral instability. The joint is generally considered to be unstable if one of the following is true: more than 25% glenoid involvement and humeral subluxation, more than 5 mm of articular surface step-off, or excessive medialization of the glenoid. Another indication for surgery is a floating shoulder, and thus ipsilateral clavicle fractures as well as AC joint separation must be considered.
The patient underwent operative fixation and his postoperative radiographs are shown in Figure 6–5.
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Figure 6–5
Which of the following statements regarding this condition is true?
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The axillary artery is the most common associated vascular injury.
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Vascular injury is more common than neurological injury.
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The mortality rate is 25%.
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If neurological function does not return, early amputation is recommended.
Discussion
The correct answer is (D). The condition that should be considered in this situation is scapulothoracic dissociation. This is typically caused by a lateral traction injury to the shoulder girdle resulting in disruption of the scapulothoracic articulation. A flail extremity, complete loss of motor and sensory function, is seen in over 50% of cases. Neurological injury is more common than vascular. The subclavian artery is the most common vascular structure injured. The mortality rate is 10%, and it is recommended that early amputation be performed if the return of neurological function is unlikely. On plain chest x-ray, a diagnosis of scapulothoracic dissociation is suggested by a scapula laterally displaced more than 1 cm from the spinous processes (in comparison to the contralateral scapula), a widely displaced clavicle fracture, acromioclavicular separation, or sternoclavicular dislocation. Advanced imaging includes angiogram which looks for an injury to either the
subclavian or axillary arteries.
Objectives: Did you learn...?
Surgical indications for scapular fractures? Diagnosis of scapulothoracic dissociation?