What is a common reason for using a flexion-extension lateral imaging in the cervical spine?

• A. Suspected ligamentous injury or instability requiring dynamic assessment
• B. To evaluate disc degeneration
• C. To view thoracic vertebrae
• D. To assess bone density

Answer: (A)

Dynamic flexion-extension lateral imaging in the cervical spine is used to evaluate stability by watching how the vertebrae move when the neck is bent forward and then extended. If ligaments and supporting structures are injured or lax, there can be excessive translation or abnormal angulation between adjacent vertebrae that isn’t seen on a single neutral view. This demonstrates instability and helps determine whether the spine is at risk for cord or nerve injury, guiding management.

Other uses aren’t the primary purpose of this technique. Disc degeneration is best assessed with MRI, not by dynamic motion study. Viewing thoracic vertebrae falls outside the cervical motion study’s target, and bone density evaluation is done with dedicated tests like DEXA, not with flexion-extension imaging.