Analysis of facet joint displacement during passive upper cervical mobilization

This study aimed to describe the amount, trajectories and reliability of the upper cervical spine mobilisations in axial rotation and flexion-extension directions in terms of combined rotational and translational motion components. Twenty fresh human cervical specimens were investigated in a test-retest situation, using an ultrasound-based motion tracking system. The amount and trajectories of C0-C1 and C1-C2 displacement were calculated along the XYZ axes were calculated. The mean NORM values of displacement varied between 7mm and 23mm for left and right facets separately. Descriptive statistics displayed wide ranges and high standard deviations. No statistically significant in a Friedman two-way ANOVA test was found. The amount of displacement in the atlanto-axial and atlanto-occipital joints were very variable among subjects. Therapists produced on average similar magnitudes of displacement, this was only partially reproducible and predictable. Trajectories showed interdependency between left and right facet displacements.