Today, let’s focus on the case of a 36-year-old woman who presents to the emergency department after a motor vehicle collision, exhibiting significant neck pain and symptoms suggestive of cervical spine injury. Can you identify the common mechanisms of injury associated with fractures of the axis (C2) and discuss the potential complications that may arise from such injuries? Additionally, sharpen your ability to recognize this fracture on a radiograph. Enhance your understanding of this critical topic in trauma and orthopedic medicine.
A 36-year-old woman who has no significant past medical history presents to the emergency department for evaluation following a motor vehicle collision. According to emergency medical services, the patient was the unrestrained driver of a vehicle traveling approximately 45 miles per hour that hit the back of a stationary truck. Upon arrival, the patient is boarded, collared, and states she has pain in the back of the neck. The patient states, “My neck is killing me. I slammed my chin on the steering wheel”. Temperature is 37.0°C (98.6°F), pulse is 104/min, respirations are 21/min, blood pressure is 172/94 mmHg, and oxygen saturation is 97% on room air. A cervical spine radiograph is shown below.
Which of the following is the most likely diagnosis?
A. Odontoid fracture
B. Burst fracture of C1
C. Spondylolisthesis of C2
D. Avulsion fracture of C3 spinous process
E. Vertebral body compression fracture of C2
Scroll down for the correct answer!
The correct answer to today’s USMLE® Step 2 CK Question is…
C. Spondylolisthesis of C2
Before we get to the Main Explanation, let’s see why the answer wasn’t A, B, D, or E. Skip to the bottom if you want to see the correct answer right away!
Incorrect Answer Explanations
Today’s incorrect answers are…
A. Odontoid fracture
Incorrect: The odontoid process, or dens, is a superior projecting bony element from the second cervical vertebrae that may become fractured during hyperextension or hyperflexion injuries. An associated fracture of the dens is not apparent on this radiograph. It is best identified on CT imaging of the head and neck.
B. Burst fracture of C1
Incorrect: A burst fracture of C1 is also known as a Jefferson fracture. It can be an unstable cervical spine injury, but typically is not and is treated with a collar. This injury more commonly occurs after a direct compression force is applied to the top of the head, and it may be difficult to identify on radiographs.
D. Avulsion fracture of C3 spinous process
Incorrect: An avulsion fracture of a spinous process, also referred to as a “clay-shoveler fracture,” is a rare fracture that is considered a stable cervical spine injury. There is no evidence of a C3 spinous process fracture in this patient’s radiograph.
E. Vertebral body compression fracture of C2
Incorrect: Vertebral body compression fractures most commonly arise in patients with underlying osteoporosis. They appear as a wedge-shaped vertebral body on radiographic imaging.
Main Explanation
This patient presents after a motor vehicle collision wherein she likely sustained a hyperextension injury to the neck. The radiograph demonstrates spondylolisthesis of the C2 vertebra, which can be an unstable cervical spine injury. However, this type of fracture typically does not cause spinal cord injury.
Traumatic spondylolisthesis and associated fractures of the C2 vertebra are also known as “hangman’s injuries” or “hangman’s fracture”–since this was a common finding in post-mortem autopsies of criminals executed by hanging. This injury pattern now most commonly occurs from car crashes and falls. It is caused by forcible hyperextension of the head, usually with the distraction of the neck or without distraction of the neck but with axial loading.
The fracture typically occurs in the axis’s superior and inferior articular processes, with an associated displacement of the C2 vertebra anteriorly on C3. Spinal cord or brainstem injury can occur if the fracture is unstable. Radiographically, it can be identified by anterior displacement of the C2 vertebra relative to C3. If the fracture is stable, then treatment is typically conservative with external fixation or bracing.
Major Takeaway
Traumatic spondylolisthesis and associated fractures of the C2 vertebra are known as “hangman’s injuries” or “hangman’s fracture”. This injury typically results from forcible hyperextension of the neck.
References
- Bransford, R.J., Alton, T.B., Patel, A.R., Bellabarba, C. (2014) Upper cervical spine trauma. The Journal of the American Academy of Orthopedic Surgeons. 22(11), 718-729. Doi: 10.5435/JAAOS-22-11-718.
- Murphy, H., Schroeder, G.D., Shi, W.J., et al. (2017) Management of hangman’s fractures: A systematic review. Journal of Orthopedic Trauma. 31 Suppl 4, S90-S95. Doi: 10.1097/BOT.0000000000000952.
- Walls, R., Hockberger, R., Gausche-Hill, M. (2017) Rosen’s emergency medicine: Concepts and clinical practice. Philadelphia, PA: Elsevier. ISBN: 978-0323354790.
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