title: Material sensitivity study on lumbar motion segment (L2-L3) under sagittal plane loadings using probabilistic method.
abstract: OBJECTIVE
  In this study, the probabilistic responses of a three-dimensional finite element L2-L3 motion segment, with and without posterior elements, tested under sagittal plane loadings, are presented. Understanding the effect of biologic uncertainties and variations on the biomechanical response provides an insight into spinal behavior under normal and degenerated conditions.
  
  
  METHODS
  The biologic variability of 19 spinal components (nucleus, annulus, ligament, cortical/cancellous bone, endplate, and ligaments) in the motion segment was incorporated using statistical distributions into the model. A total of 2000 runs were performed using Monte Carlo probabilistic algorithms to compute the probabilistic response.
  
  
  RESULTS
  This study establishes the relative importance of the spinal components in resisting the loading modes. The results show that for an intact motion segment, posterior ligaments are more dominant than intervertebral disc in resisting flexion moment. In extension, the capsular ligaments were found to be the most influential parameter. The intervertebral disc (ie, nucleus and annulus) affects the angular response of the disc body segment more than the hard tissues (ie, cortical and cancellous bone).
  
  
  CONCLUSIONS
  The application of the probabilistic analysis provides a new approach whereby the influences of inherent uncertainties and variations in biologic structures can be studied and the biomechanical response assessed.
authors.affiliation: From the School of Mechanical and Production Engineering, Nanyang Technological University, Singapore.
authors.forename: Kim K
authors.initials: KK
authors.lastname: Lee
authors.forename: E Chon
authors.initials: EC
authors.lastname: Teo
mesh_terms: D020342:Finite Element Analysis; D006801:Humans; D007403:Intervertebral Disc / Q000033:anatomy & histology / Q000502:physiology*; D008022:Ligaments / Q000033:anatomy & histology / Q000502:physiology; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D009068:Movement / Q000502:physiology*; D013131:Spine / Q000033:anatomy & histology / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology; D021801:Zygapophyseal Joint / Q000033:anatomy & histology / Q000502:physiology