In Vivo Three-Dimensional Kinematics of the Cervical Spine During Head Rotation in Patients With Cervical Spondylosis

Study Design. Kinematics of the cervical spine during head rotation was investigated using 3-dimensional (3D) magnetic resonance imaging (MRI) in patients with cervical spondylosis (CS). Objective. To demonstrate in vivo 3D kinematics of the spondylotic cervical spine during head rotation. Summary of Background Data. Several in vivo studies have identified kinematic differences between normal and spondylotic subjects, but only two-dimensional flexion/extension motion has been investigated. Differences of in vivo 3D cervical motion during head rotation between normal and spondylotic subjects have yet to be clarified. Methods. Ten healthy volunteers (control group) and 15 patients with CS (CS group) underwent 3D MRI of the cervical spine with the head rotated to 5 positions (neutral, +/- 45 degrees and +/- maximal head rotation). Relative motions of the cervical spine were calculated by automatically superimposing a segmented 3D MRI of the vertebra in the neutral position over images for each position using volume registration. The 3D motions of adjacent vertebra were represented with 6 degrees of freedom by Euler angles and translations on the coordinate system. Results. Compared with the control group, the CS group showed significantly decreased mean axial rotation and mean coupled lateral bending at C5-C6 and C6-C7 and significantly increased mean coupled lateral bending at C2-C3 and C3-C4, although both the groups showed the same pattern of coupled motions. Conclusion. The in vivo 3D kinematics of the spondylotic cervical spine during head rotation was accurately depicted and compared with those of healthy cervical spines for the first time.