ABSTRACT
Objective To simulate the cervical rotatory manipulation(CRM)in flexion,neutral and extension positions using three-di-mensional finite element,so as to investigate the effect of this manipulation on the displacement and intra-stress of cervical disc in different positions.Methods By using the method of reverse engineering with Mimics 10.01,Geomagic Studio and Solidworks 14.0,a three-dimen-sional geometric CAD model of C5-6was developed from the CT scan images of a normal adult female aged 25 years.The model was import-ed into Ansys Workbench 14.5,and a three-dimensional finite element model was verified and simulated the CRM.The CRM was decom-posed by principium of manipulation in flexion,neutral and extension,respectively.The parameter of mechanics was analyzed with the fi-nite element system.The change of displacement and intra-stress distribution in cervical disc simultaneous were displayed during simulating the manipulation.Results The posterior part of opposite rotary side of annulus fibers was all retracted,and the displacement was toward an-terior,maximal in flexion position,followed as neutral position and minimal in extension position.In the meantime,the posterior part of the rotary side of annulus fibers was expanded into posterior,minimal in flexion position,followed as neutral position and maximal in extension position.The intra-stress in cervical disc was focused on posterior part of opposite rotary side,opposite rotary side and posterior part of the rotary side in flexion position,neutral position and extension position,respectively,maximal in flexion position,followed as extension posi-tion and minimal in neutral position. Conclusion To treat with cervical spondylotic radiculopathy in the perspective of safety of cervical disc,the CRM should rotate to the unaffected side,first in neutral position,second in flexion position if with poor efficacy.Patients with cer-vical spinal stenosis should not be treated with the CRM.