Friday, September 28, 2018 8:00 AM–9:00 AM interdisciplinary spine forum: abstract presentations: 144. Biomechanical effects of lateral bending position on performing cervical spinal manipulation for cervical disc herniation: a three-dimensional finite element analysis

Abstract

BACKGROUND CONTEXT Most studies report that the common position of cervical spinal manipulation (CSM) for treating symptomatic cervical disc herniation (CDH) is lateral bending to the herniated side. However, the rationality of lateral bending position on performing CSM for CDH is still unclear. PURPOSE The purpose of this study is to investigate the biomechanical effects of lateral bending position on performing CSM for CDH. STUDY DESIGN/SETTING A finite element analysis study. OUTCOME MEASURES Cervical disc displacement, annulus fiber stress (von Mises stress) and facet joint stress (von Mises stress) were observed during the simulation of CSM. METHODS Afinite element (FE) model of CDH (herniated on the left side) was generated in C5–C6 segment based on the normal FE model. The FE model was performed CSM in left lateral bending position, neutral position and right lateral bending position, respectively. Cervical disc displacement, annulus fiber stress and facet joint stress were observed during the simulation of CSM. RESULTS The cervical disc displacement on herniated side moved forward during CSM, and the maximum forward displacements were 0.23, 0.36 and 0.45mm in left lateral bending position, neutral position and right lateral bending position, respectively. As the same trend of cervical disc displacement, the annulus fiber stress on herniated side from small to large were 7.40, 16.39 and 22.75MPa in left lateral bending position, neutral position and right lateral bending position, respectively. However, the maximum facet stresses at left superior cartilage of C6 in left lateral bending position, neutral position and right lateral bending position were 6.88, 3.60 and 0.12MPa, respectively. CONCLUSIONS Compared with neutral position and right lateral bending position, though the forward displacement of cervical disc on herniated side was smaller in left lateral bending position, the annulus fiber stresson herniated sidewas declined by sharing load on the left facet joint. The results suggested that lateral bending to the herniated side on performing CSM tend to protect the cervical disc on herniated side. Future clinical studies are in need to verify that.