Differences in Cervical Spine Vertebral Center of Rotation Location During Flexion and Extension Movements in Asymptomatic Controls

Abnormal cervical spine motion may occur as the result of injury or degenerative changes in symptomatic patients. Intervertebral range of motion (ROM) is a standard metric used to evaluate abnormal spine motion, but can only describe the amount of motion and not the quality of motion. In addition, significant variability in normal ROM among subjects may minimize the efficacy of this parameter in identifying abnormalities in symptomatic patient groups¹. Instead, the instant center of rotation (ICR) has been proposed as a reliable, stable measurement of the quality of vertebral motion through which abnormalities could be explored².