Effect of cervical rotatory direction on the displacement of cervical disc and the volume of intervertebral foramen in a three-dimensional finite element model / 中国组织工程研究

ABSTRACT

BACKGROUND: Cervical spondylotic radiculopathy could be effectively treated by cervical rotatory manipulation, but the symptoms may be exacerbated when rotated to the wrong direction. OBJECTIVE: To simulate the cervical rotatory manipulation in left/right rotation by three-dimensional finite element, and then investigate the effect of this manipulation on the displacement of cervical disc and the volume of intervertebral foramen so as to provide a basis for effectiveness and safety of cervical rotatory manipulation in treating cervical spondylotic radiculopathy. METHODS: With Mimics10.01, Geomagic Studio and Solidworks 14.0 software, a three-dimensional geometric CAD model of C5-6was developed from the CT scan images of a 25-year-old normal adult female. The model was imported into Ansys Workbench 14.5, and a three-dimensional finite element model was verified and simulated the cervical rotatory manipulation. The cervical rotatory manipulation was decomposed by principium of manipulation in left lateral flexion and rotated to the left/right side. The parameter of mechanics was analyzed with the finite element system. The change of displacement in cervical disc and volume in intervertebral foramen simultaneously were displayed during simulating the manipulation. RESULTS AND CONCLUSION: In left lateral flexion and rotated to the left side, the posterior part of the left side of annulus fibers was expanded 0.46 mm into posterior, and the posterior part of the right side of annulus fibers was retracted 0.77 mm. The volume of left intervertebral foramen became small and the right side became large. However, in left lateral flexion and rotated to the right side, the posterior part of the left side of annulus fibers was retracted 0.71 mm, and the posterior part of the right side of annulus fibers was expanded 0.43 mm into posterior. The volume of left intervertebral foramen became large and the right side became small. Therefore, the posterior part of the rotated side of cervical disc was expanded into posterior, while the posterior part of the contralateral side of cervical disc was retracted. The volume of intervertebral foramen in rotated side became small, while the volume of intervertebral foramen in contralateral side became large. We should rotate to the contralateral side when cervical spondylotic radiculopathy was treated with cervical rotatory manipulation.