Cervical spine segmental vertebral motion in healthy volunteers feigning restriction of neck flexion and extension.

The purpose of this study was to obtain comparative data concerning the percentage contribution of segmental cervical vertebral motion to the cervical range of motion (ROM) in healthy volunteers under two conditions: (1) normal, voluntary neck flexion and extension and (2) feigned restriction of neck flexion and extension. Each healthy subject's angular motion over forward cervical flexion and extension was measured first by X-ray analysis during normal, voluntary motion. Then the subjects were asked to pretend that they had a 50% restricted neck range due to pain or stiffness and thus to move in both flexion and extension only as far as about 50% of their normal range.