Abnormal instantaneous axes of rotation in patients with neck pain.

Instantaneous axes of rotation for cervical motion segments C2-3 to C6-7 were determined in 109 patients with uncomplicated neck pain. Their location in each patient was compared to normal ranges determined in a previous study of 46 asymptomatic individuals. Unequivocally abnormal instantaneous axes of rotation were found in 46% of patients, and marginally abnormal instantaneous axes of rotation were found in a further 26% of patients. Abnormal instantaneous axes of rotation significantly correlated with the presence of neck pain, but the location of an abnormal axis did not correlate with the segmental source of pain as determined by provocation discography or zygapophyseal joint blocks.