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 flexion-extension 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. (C) 2011 Elsevier Ltd. All rights reserved.