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BACKGROUND: Positions of cervical rotatory manipulation mainly include flexion, neutral, extension and rotation direction. It is still not clear which positions are more beneficial for cervical rotatory manipulation to reduce facet joint displacement in treatment of cervical spondylotic radiculopathy. OBJECTIVE: To compare biomechanical effects of positions on reduction of facet joint displacement by cervical rotatory manipulation in treatment of cervical spondylotic radiculopathy. METHODS: A three-dimensional finite element model of the normal C5-C6 was constructed and validated. Cervical rotatory manipulation was simulated with rotation to the right side in flexion, neutral and extension, respectively. Displacement distributions in forward-backward and upward-downward directions of C5 bilateral inferior articular processes were compared among cervical rotatory manipulation performed in different positions. The same node in C5 inferior articular process of the reduced side was selected as reference point for displacement value. Displacement values in forward-backward and upward-downward directions of C5 inferior articular process of the reduced side were compared among cervical rotatory manipulation performed in different positions. RESULTS AND CONCLUSION: (1) With cervical rotatory manipulation performed in flexion, neutral and extension, ipsilateral C5 inferior articular process of rotation moved backward and downward while contralateral C5 inferior articular process of rotation moved forward and upward. Thus, the sliding trend of C5 inferior articular process was significantly correlated with the direction of rotation, but not with positions of flexion, neutral and extension. (2) When cervical rotatory manipulation was performed in flexion, neutral and extension, forward displacement of contralateral C5 inferior articular process of rotation was 1.32, 1.22 and 0.77 mm, respectively, and upward displacement was 1.49, 1.29 and 0.29 mm, respectively. (3) The findings showed that forward-upward displacement of contralateral inferior articular process of rotation was maximum in flexion, indicating that rotation to the healthy side in flexion might be more beneficial for cervical rotatory manipulation to reduce facet joint displacement in treatment of cervical spondylotic radiculopathy. [ABSTRACT FROM AUTHOR]

Objective To simulate the cervical rotatory manipulation (CRM) in left/right lateral bending position by using the three-dimensional finite element, so as to investigate the effect of lateral bonding position on the displacement and intra-stress of cervical disc when performing CRM. Methods With MimieslO.Ol , Geomagic Studio, and Solidworks 14.0 software, a three-dimensional finite element model of C5-6 was developed from the CT scan images of a 25-year-old normal adult female. The model was imported into Ansys Workbench 14.5 to verify and simulate the CRM. The CRM was decomposed by prineipium of manipulation in left/right lateral flexion and rotated to the right side. The parameter of mechanics was analyzed with the finite element system. The change of displacement and intra-stress distribution in cervical disc simultaneously were displayed during simulating the manipulation. Results In left/right lateral bending position and rotated to the right side, the posterior part of the left side of cervical disc was all retracted. And the displacement was toward anterior, left lateral flexion (0.93 mm) was smaller than the right lateral flexion (1.12 mm). The intra-stress of cervical disc wen: focused on the posterior part of the right side and the left side in left/right lateral flexion, respectively, and the maximum strews of left lateral bending (7. 00 MPa) was smaller than that of the right lateral bending (8. 19 MPa). Conclusion When the cervical vertebra is in the left lateral bending position and mtates to the right side, the effects on the displacement and intra-stress are smaller than that of the right lateral bending position. Therefore, the left lateral bending position is more likely to protect the left side of cervical disc. When we treat cervical spondylotic radiculopathy with CRM, should let the patients rotate to the contralateral side with lateral flexion to the ipsilateral side. In this way, it can alleviate the symptom, and reduce the risk of secondary injury to the cervical disc of ipsilateral side at the same time. [ABSTRACT FROM AUTHOR]