Morphology and kinematics of the atlanto-axial joints and their interaction during manual cervical rotation mobilization

Background data: At present little data are available on the relationship between spinal anatomy and kinematics. No studies have verified the relationship between atlanto-axial kinematics during manual mobilization and the spatial features of the atlanto-axial ligaments and the lateral joints. Materials and methods: Twenty un-embalmed cervical spine specimens (9 male and 11 female; 80 +/- 11 years) were studied. Atlanto-axial kinematics were registered during manual axial rotation mobilization using an ultrasound-based motion tracking system. Anatomical landmarks were digitized and spatial features of the lateral atlanto-axial joint surfaces and alar ligaments were extracted. The relationship between the anatomical features and the spinal kinematics was analyzed using statistical regression analysis. Results: Only the range of motion of the coupled flexioneextension motion component, the ratio and the time shift between main axial rotation and coupled lateral bending motion components could be predicted for about 52%, 49% and 73%, respectively, by a selected set of anatomical features. Conclusion: Supposed relationships between anatomical features and joint kinematics are only partially confirmed. The results indicate that the kinematics of the atlanto-axial joint during manual regional axial mobilization are not completely predetermined by the specimens' specific anatomy.