title: Assessment of stress patterns on a spinal motion segment in healthy versus osteoporotic bony models with or without disc degeneration: a finite element analysis.
abstract: BACKGROUND
  With an increasing prevalence of low back pain, physicians strive to optimize the treatment of patients with degenerated motion segments. There exists a consensus in literature that osteoporotic patients exhibit nonphysiologic loading patterns, while degenerated intervertebral discs (IVDs) are also believed to alter spine biomechanics.
  
  
  OBJECTIVE
  To evaluate alterations occurring in lumbosacral spine biomechanics of an osteoporotic model, with or without IVD degeneration, when compared with a healthy spine segment.
  
  
  METHODS
  The investigation was based on finite element (FE) analysis of a patient-specific lumbosacral spine model.
  
  
  METHODS
  A biorealistic model of a lumbosacral spine segment is introduced to determine the morbidity of disc degeneration and osteoporosis. The model was verified and validated for the purpose of the study and subjected to a dynamic FE analysis, considering anisotropic bone properties and solid ligamentous tissue.
  
  
  RESULTS
  The yielded results merit high clinical interest. Osteoporosis resulted in a nonuniform increase of facet joint loading, which was even more pronounced in the scenario simulating a degenerated disc. The results also revealed an enslavement of intradiscal pressure to the disc state (in the degenerated and superior adjacent level).
  
  
  CONCLUSIONS
  The investigation presented refined insight into the dynamic biomechanical response of a degenerated spine segment. The increase in the calculated occurring stresses was considered as critical in the motion segment adjacent and superior to the degenerated one. This suggests that prevalent trauma in a motion segment may be a symptomatic condition of a poorly treated formal pathology in the inferior spine level.
authors.affiliation: Mechanical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece. Electronic address: alextso@auth.gr.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tsouknidas
authors.affiliation: Mechanical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: Stylianos Orestis
authors.initials: SO
authors.lastname: Sarigiannidis
authors.affiliation: University Hospital Llandough, Cardiff University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK.
authors.forename: Kleovoulos
authors.initials: K
authors.lastname: Anagnostidis
authors.affiliation: Mechanical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Michailidis
authors.affiliation: University Hospital Llandough, Cardiff University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK.
authors.forename: Sashin
authors.initials: S
authors.lastname: Ahuja
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D020342:Finite Element Analysis; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000473:pathology / Q000503:physiopathology*; D017116:Low Back Pain / Q000473:pathology / Q000503:physiopathology*; D008953:Models, Anatomic; D010024:Osteoporosis / Q000473:pathology / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D013131:Spine / Q000473:pathology / Q000503:physiopathology*; D013314:Stress, Mechanical; D021801:Zygapophyseal Joint / Q000473:pathology / Q000503:physiopathology*
keywords: Facet loading; Finite element analysis; Intervertebral disc degeneration; Lumbosacral spine; Non-linear model; Spine biomechanics