Cervical spine (flexion and extension views)

The cervical spine flexion and extension views demonstrate the seven vertebrae of the cervical spine when the patient is in a lateral position.

Indications

These views are specialized projections often requested to assess for spinal stability.

Note: Such functional views should not be performed on trauma patients without the strict instructions of a qualified clinician.

Patient position

• the patient is erect, left side against the upright detector 
• the detector is placed portrait, parallel to the long axis of the cervical spine on the patients left side 
• the patient will have the neck in the extended (chin up) or flexion (chin down) position depending on the projection

Technical factors

• lateral projection
• centering point
  • 2.5 cm above the jugular notch at the level of C4
• collimation
  • superior to C1
  • inferior to T1
  • anterior to include soft tissue
  • posterior to the soft tissue
• orientation  
  • portrait 
• detector size
  • 24 cm x 30 cm
• exposure
  • 50-75 kVp
  • 20-50 mAs
• SID
  • 150-180 cm
• grid
  • yes

Image technical evaluation

• there should be clear visualization of C7 to T1
• the image is labeled as 'flexion' or 'extension'  
• flexion images should demonstrate well separated spinous process 
• extension images should demonstrate crowding of the spinous process

Practical points

• demonstrate to the patient what flexion and extension is before performing 
• ensure the patient is aware when the examination is over as to avoid extended periods of time in that position 
• patients who feel unstable on their feet can sit in a chair for this examination 
• ensure this radiographic series is safe to perform, i.e. part of a secondary survey or under the guidance of an authorized physician 
• more than 3.5 mm of intersegmental translation (a summation of the displacement observed between vertebra tracing the posterior line on both the flexion and extension view) is considered unstable