Cervical spine flexion patterns.

Lateral projection flexion and extension radiographs of the cervical spine are stress views. They are necessary to evaluate unstable ligamentous injury, which may not be apparent on neutral unstressed films. As there is very little literature on the proper evaluation of these radiographic views, we reviewed 150 consecutive cases from our Emergency Department to define patterns of flexion. Four significantly different patterns emerged. No flexion at any level was seen in 24.7% of patients. A single flexion angle was seen in 24.7% Two flexion angles, usually at consecutive levels, were present in 29.3% of patients, and 21.3% had three or more flexion angles. Correlation with clinical data suggests that attempted flexion with no significant angle or a single angle is abnormal and may indicate soft tissue (ligament or muscle) injury. Three or more flexion angles are thought to represent a normal pattern. The most common pattern, two flexion angles at consecutive levels, has not been previously described. We believe this pattern indicates less than full flexion and can be seen in individuals without significant injury and in those limited by mild soft-tissue injury.