Does manual mobilization influence motion coupling patterns in the atlanto-axial joint?

Background: A restricted number of publications have reported on the analysis of coupling patterns in the atlanto-axial joint using an in vitro set-up applying pure moments of forces. The aim of this study is to analyze segmental motion coupling patterns during cervical manual mobilization. Methods: The position and attitudes of sensors mounted on the atlas and axis were traced in nine embalmed and one fresh human spinal specimen using an electromagnetic tracking system. Segmental bony reference points were registered using a 3D-digitizing stylus for the definition of bone embedded coordinate systems. Segmental motion coupling was recorded for the atlanto-axial joints during manual mobilization through the full range of axial rotation and lateral bending. Results: Coupled motions were described by the direction of the associated motion and by cross-correlation analysis. The results confirm the contra-lateral coupling pattern of axial rotation with lateral bending at C1-C2 observed in previous studies. The cross-correlation analysis offered a more objective interpretation of the coupling pattern for the analysis of the more irregular coupling patterns during lateral bending. Inter-individual differences in coupling patterns were observed. Interpretations: The presented method provides possibilities for the study of coupled motion during manual diagnostic and therapeutic practice. Practitioners should be aware of the segmental 3D-aspects of manually induced so called planar mobilizations and their possible influence on motion coupling. Motion coupling patterns may be related to specimen specific anatomy. (C) 2007 Elsevier Ltd. All rights reserved.