Morphometric changes of the cervical intervertebral foramen: A comparative analysis of pre-manipulative positioning and physiological axial rotation

Background: Cervical foraminal impingement has been described as a source of radicular pain. Clinical tests and head motions have been reported for affecting the intervertebral foramen (IVF) dimensions. Although manual approaches are proposed in the management of cervical radiculopathy, their influence on the foraminal dimensions remains unclear. Objectives: To investigate the influence of pre-manipulative positioning versus cervical axial rotation on the foraminal dimensions of the lower cervical spine. Methods: Thirty asymptomatic volunteers underwent CT scan imaging in neutral position and axial rotation or pre-manipulative positioning. The manipulation task was performed at C4-C5 following a multiple components procedure. 3D kinematics and IVF (height, width and area) were computed for each cervical segment. Results: The results showed that foraminal changes are dependent on motion types and cervical levels. With reference to head rotation, IVF opening occurred on the ipsilateral side during pre-manipulative positioning while axial rotation involved the contralateral side. Regardless of the side considered, magnitudes of opening were similar between both attitudes while narrowing was lower at the target and adjacent levels during the pre-manipulative positioning. Some associations between segmental motion and IVF changes were observed for the target level and the overlying level. Conclusions: The present study demonstrated that pre-manipulative positioning targeting C4-C5 modified IVF dimensions differently than the passive axial rotation. The findings suggest that techniques which incorporate combined movement positioning influence segmental motion and IVF dimensions differently at the target segment, compared to unconstrained rotation. Further investigations are needed to determine the clinical outcomes of such an approach.