THREE-DIMENSIONAL ANALYSIS OF COUPLING BEHAVIOUR OF CERVICAL SPINE ARTHROKINEMATICS IN COMMON CLINICALLY RELEVANT THERAPEUTIC POSITIONS: PART I SOLID MODELS ANALYSIS.

¹Cairo University, Physical Therapy for Neuromuscular Disorders and its Surgery, Cairo, Egypt

Background: Understanding Coupling behaviours of the cervical spine motion segments is of great value during manual and exercise therapy either in assessment or treatment. Coupling behaviours is a phenomenon in which primary movement results in a joint also moving in other directions and one motion cannot be produced without the other.

Purpose: The first aim of these study was to visualize and analyse the coupling behaviour of cervical spine in common clinically relevant therapeutic positions. The second aim was to study its effect on facet joints and intervertebral discs spaces.

Methods: Fifteen healthy subjects have been subjected to 3D CT scan from 6 separate positions in two visits to Radiology lab, 3 positions in each visit to avoid overdose of exposure to X ray. The six positions were: Neutral (N) position, Lateral bending (LB), Axial rotation (AR), Flexion and bending with ipsilateral rotation to opposite side of bending (FBI), Flexion and bending with contralateral rotation (FBC), and Extension with contralateral rotation (ECR). CT volumes have been reconstructed with image thickness 1.0 mm and 0 gap between slices. Direction of CT scan volumes reconstruction was 45 degrees with para sagittal plan and 10 to 15 degrees below the transverse plane to visualize plan of intervertebral foramens (IVFs).

Results: When Spine was in Neutral or Flexion and primary axis was contralateral rotation to one side: relative side bend to the same direction of rotation in all levels has been noted, the atlas followed head movement in full range of rotation, with mild degrees of rotation to the same side in vertebrae C2 to C5, while the lower cervical segments from C6 to T1 were been in rotation to the opposite side (convex side). When spine was in neutral and primary axis is lateral bending to one side, no rotation noted in the Atas, with a horizontal rotation of C3-5 to the same side (concave side) while C6-7-T1 were been in horizontal rotation to the opposite side (convex side). When spine was in flexion, lateral bending and Ipsilateral rotation to the opposite side of bending, the atlas follows the head movement to ipsilateral rotation in full range, while all the remaining vertebrae were been in rotation and bending to the opposite side of rotation with no concavity or concavity.

Conclusions: During multiplanar therapeutic positions of manual therapy as in AR, FBI, FBC and ECR positions, results were inconsistent with Fryette' s principles if the primary axis has been changed to axial rotation instead of lateral bending, Facet joints and disc spaces were in open packed positions in the convex side of lateral bending obviously in the presence of forward flexion. And vice versa in the concave side.

Implications: ​​​​Intended multiplanar therapeutic positions has different arthrokinematics inconsistent with Fryette' s principles of coupling movements in cervical spine. Atlas vertebra directly follow head position either in rotation or tilting. vertebrae from C2 to C 5 moves together with similar behaviour at the same direction of bending, while Vertebrae C6, C7, T1 have coupling behaviour opposite to it except in FBI position.

Funding acknowledgements: ElRazzy Spine physical therapy and rehabilitation clinics

Keywords:
Coupling movement
Intervertebral foramen
Fryette' s principles

Topics:
Musculoskeletal: spine

Did this work require ethics approval? Yes

Institution: Cairo University

Committee: Faculty of physical therapy Research Ethical committee

Ethics number: P.T.REC/012/003793