Scapulothoracic Disassociation: A Rare and Devastating Injury

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Image Credit: Emergency Medicine: Open Access

The Case
Trauma Activation: A 25-year-old motorcyclist traveling approximately 75 miles per hour lost control and the motorcycle slid from underneath him. His entire right side made primary contact with the road. Upon arrival, he was awake and able to participate in his examination. His left upper extremity was pulseless with a complete loss of motor function and sensation. 

Left Scapulothoracic Dissociation – a traumatic disruption of the scapulothoracic articulation often associated with:

  • other orthopedic injuries including those to the acromioclavicular joint, clavicle, scapula, and sternoclavicular joint,
  • vascular injuries particular to the subclavian and axillary arteries,
  • neurologic injuries especially to the ipsilateral brachial plexus.[1,2] 

Due to the significant force required to cause this injury, it can be difficult for emergency medicine physicians to identify scapulothoracic dissociation amidst the many other injuries. As a result, the patient’s participation in the exam may be limited. Initial evaluation should follow standard Advanced Trauma Life Support protocol. If the patient is able to participate, a careful neurological examination is important to evaluate for neurological injury and to identify the level of the injury. If there is vascular injury (present in 88% of cases) a pulseless extremity may be noted on exam.[3] However in the setting of shock, the identification of a pulseless extremity may not be readily apparent if the entire patient is cool and mottled with weak pulses. If the injury is not initially identified on a polytrauma patient, standard radiographs obtained in the trauma bay may aid in diagnosis. On imaging of the chest, lateral displacement of the scapula is pathognomonic.[4]

The types of injuries will dictate which consults are most appropriate (vascular, thoracic trauma, orthopedics). If the patient is stable, CT angiogram can aid in location of vascular injury. Surgical consult teams will determine the next steps in the operating room.

The prognosis of the injury depends on neurologic injury.[1] If there is a complete disruption of the brachial plexus, there is negligible hope for recovery. The literature recommends early amputation in these situations.[1]

Although rare, scapulothoracic dissociation is a devastating injury and one that emergency medicine physicians should be aware of to avoid missing or delaying diagnosis.

Case Conclusion
Left arm angiography identified a left subclavian occlusion and the patient was taken to the operating room for surgical exploration. It was hypothesized that the left arm injury occurred as he was trying to hold on to the handlebar as he was being thrown from the motorcycle.