title: Real-time monitoring of stresses and displacements in cervical nuclei pulposi during cervical spine manipulation: a finite element model analysis.
abstract: OBJECTIVE
  The objective of this study was to research the distribution of stresses and displacements in cervical nuclei pulposi during simulated cervical spine manipulation (CSM).
  
  
  METHODS
  A 3-dimensional finite element model of C3/4~C6/7 was established. The detailed mechanical parameters of CSM were analyzed and simulated. During the process, the changes in stresses and displacements of cervical nuclei pulposi within the model were displayed simultaneously and dynamically.
  
  
  RESULTS
  Cervical spine manipulation with right rotation was targeted at the C4 spinous process of the model. During traction, levels of stresses and displacements of the nuclei pulposi exhibited an initial decrease followed by an increase. The major stresses and displacements affected the C3/4 nucleus pulposus during rotation in CSM, when its morphology gradually changed from circular to elliptical. The highest stress (48.53 kPa) occurred at its right superior edge, on rotating 40° to the right. It protruded toward the right superior, creating a gap in its left inferior aspect. The highest displacement, also at 40° right, occurred at its left superior edge and measured 0.7966 mm. Dimensions of stresses and displacements reduced quickly on rapid return to neutral position.
  
  
  CONCLUSIONS
  The morphology of the C3/4 nucleus pulposus changed during CSM with right rotation, and it created a gap in its left inferior aspect. Biomechanically, it is more safe and rational to rotate toward the healthy side than the prolapsed side of the intervertebral disk during CSM. Upon ensuring due safety, the closer the application force is to the diseased intervertebral disk, the better is the effect of CSM.
authors.affiliation: Associate Professor, Department of Orthopedics, Jiangmen Central Hospital of Guangdong Province China (Affiliated Jiangmen Hospital of Sun Yat-Sen University), Jiangmen, Guangdong, PR China. Electronic address: 12303383@qq.com.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Wu
authors.affiliation: Professor, Department of Orthopedics, Jiangmen Central Hospital of Guangdong Province China (Affiliated Jiangmen Hospital of Sun Yat-Sen University), Jiangmen, Guangdong, PR China.
authors.forename: Yuan-Qiao
authors.initials: YQ
authors.lastname: Huang
authors.affiliation: Associate Professor, Department of Anatomy, Sanford School of Medicine, University of South Dakota, Vermillion, SD.
authors.forename: Das
authors.initials: D
authors.lastname: Manas
authors.affiliation: Associate Professor, Department of Orthopedics, Jiangmen Central Hospital of Guangdong Province China (Affiliated Jiangmen Hospital of Sun Yat-Sen University), Jiangmen, Guangdong, PR China.
authors.forename: Yong-yuan
authors.initials: YY
authors.lastname: Chen
authors.affiliation: Associate Researcher, Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, PR China.
authors.forename: Ji-hong
authors.initials: JH
authors.lastname: Fan
authors.affiliation: Physician-in-charge, Department of Orthopedics, Jiangmen Central Hospital of Guangdong Province China (Affiliated Jiangmen Hospital of Sun Yat-Sen University), Jiangmen, Guangdong, PR China.
authors.forename: Hua-gui
authors.initials: HG
authors.lastname: Mo
mesh_terms: D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae; D003198:Computer Simulation; D020342:Finite Element Analysis; D007403:Intervertebral Disc / Q000502:physiology*; D020393:Manipulation, Spinal; D013314:Stress, Mechanical
keywords: Cervical Vertebrae; Displacement; Finite Element Analysis; Manipulation; Nucleus Pulposus; Spinal; Stress