Exploring the biomechanical mechanisms of cervical rotation manipulation in different lateral bending positions: a finite element analysis

Abstract

Abstract Objective To investigate the biomechanical mechanism of cervical rotation manipulation (CRM) in different lateral bending positions. Methods A 27-year-old Asian male patient with cervical spondylotic radiculopathy due to left posterior cervical disc protrusion and compression of nerve roots was recruited. The CT scan data of his skull and cervical spine were extracted to construct finite element models of the skull and whole cervical spine. After model verification, the key parameters of CRM were loaded into the model, and the effects of CRM on the structure of cervical spine were analyzed. Results In left lateral bending, neutral and right lateral bending positions, the maximum Mises stresses of C5/6 annulus fibrosus were 1.545, 0.951 and 0.917 Mpa, the maximum Mises stresses of nucleus pulposus were 0.168, 0.139 and 0.146 Mpa, and the maximum Mises stresses of facet joints were 3.973, 2.186 and 1.369 Mpa, respectively, and those of the spinal cord and nerve roots were 2.692, 2.547, and 3.150 Mpa respectively. Regarding the anterior displacement of the cervical intervertebral disc on the herniated side, the maximum values were 1.060, 1.067, and 0.865 mm respectively. For the area of the intervertebral foramen on the affected sidearea, it was 34.393 mm² before the manipulation, and after the manipulation, it was 39.588, 39.724, and 41.668 mm² under the three positions respectively. Conclusion In CRM, the neutral position enlarges the intervertebral foramen volume and reduces intervertebral disc stress, with low spinal cord and nerve root stress and injury risk. In the right lateral bending position (lateral bending on the healthy side), the stresses in the annulus fibrosus and facet joints are minimal, and the intervertebral foramen expansion is most obvious, but the stresses in the spinal cord and nerve roots are the highest. In the left lateral bending position (lateral bending on the herniated side), the stresses in the intervertebral disc and facet joints are the highest, but it is conducive to the anterior displacement of the herniated intervertebral disc and enables smoother operation. Clinicians should select the appropriate operating position according to the actual situation.

Keywords

• Biomechanical mechanisms
• Cervical rotation manipulation
• Lateral bending
• Finite element analysis