title: Correlation of vertebral strength topography with 3-dimensional computed tomographic structure.
abstract: METHODS
  Biomechanical and radiographical study.
  
  
  OBJECTIVE
  To test the hypothesis that stiffness and strength at discrete sites of human lumbar vertebrae depend on the 3-dimentional structure and density of the vertebral-body bone elements, and can be evaluated using models based on vertebral bone characteristics obtained from quantitative computed tomogrphy.
  
  
  BACKGROUND
  We have not found published methods that allow in vivo evaluation of bone mechanical properties at discrete sites of vertebral body applicable for clinical use.We hypothesize that human lumbar vertebral strength topography depends on the local 3-dimensional structural features of the bone structure, and that the stiffness and strength can be evaluated at discrete sites using models based on data obtained from quantitative computed tomographic (CT) images.
  
  
  METHODS
  Forty-eight vertebrae (8 L1, 8 L2, 8 L3, 10 L4, and 14 L5) from 14 cadaveric subjects (9 men and 5 women; age, 43-99 yr) were studied. Stiffness (modulus of elasticity) and strength (maximum load and maximum tolerable pressure) were defined by an indentation test at 11 discrete sites on the cranial and caudal surfaces of each vertebral endplate. Before the indentation test radiography, dual-energy x-ray absorptiometry, micro-CT, and conventional-CT (con-CT) of the vertebrae were performed. Micro-CT characteristics of cortical and cancellous bones of 18 vertebrae were measured at each region of interest defined by a 3-dimensional coordinate system. The most informative indices regarding endplate strength were selected by correlation analysis. Predictive models of local stiffness and strength were created using selected indices obtained by micro-CT and con-CT (40 vertebrae) images.
  
  
  RESULTS
  Local stiffness and strength of the tested specimens were highly variable. Endplate thickness and density in combination with adjacent trabecular bone density, existence of endplate defects, and subject's age were good predictors of local stiffness and strength, applicable for con-CT. Polynomial multiple regression of these characteristics provides the best correlation with stiffness (r2 = 0.82; P < 0.001) and strength (r2 = 0.74).
  
  
  CONCLUSIONS
  Stiffness and strength at discrete sites of human lumbar vertebrae depend on the superficial vertebral bone structure and density and can be evaluated using models based on quantitative analysis of micro-CT and con-CT images.
authors.affiliation: Spine Center, Department of Orthopaedics, University of Colorado, Denver, CO, USA. Andriy.Noshchenko@ucdenver.edu
authors.forename: Andriy
authors.initials: A
authors.lastname: Noshchenko
authors.forename: Atousa
authors.initials: A
authors.lastname: Plaseied
authors.forename: Vikas V
authors.initials: VV
authors.lastname: Patel
authors.forename: Evalina
authors.initials: E
authors.lastname: Burger
authors.forename: Todd
authors.initials: T
authors.lastname: Baldini
authors.forename: Lu
authors.initials: L
authors.lastname: Yun
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D019245:Compressive Strength; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D016014:Linear Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D013499:Surface Properties; D014057:Tomography, X-Ray Computed; D055114:X-Ray Microtomography