title: Tibial geometry is associated with failure load ex vivo: a MRI, pQCT and DXA study.
abstract: We studied the relations between bone geometry and density and the mechanical properties of human cadaveric tibiae. Bone geometry, assessed by MRI and pQCT, and bone density, assessed by DXA, were significantly associated with bone's mechanical properties. However, cortical density assessed by pQCT was not associated with mechanical properties.
  
  
  BACKGROUND
  The primary objective of this study was to determine the contribution of cross-sectional geometry (by MRI and pQCT) and density (by pQCT and DXA) to mechanical properties of the human cadaveric tibia.
  
  
  METHODS
  We assessed 20 human cadaveric tibiae. Bone cross-sectional geometry variables (total area, cortical area, and section modulus) were measured with MRI and pQCT. Cortical density and areal BMD were measured with pQCT and DXA, respectively. The specimens were tested to failure in a four-point bending apparatus. Coefficients of determination between imaging variables of interest and mechanical properties were determined.
  
  
  RESULTS
  Cross-sectional geometry measurements from MRI and pQCT were strongly correlated with bone mechanical properties (r(2) range from 0.55 to 0.85). Bone cross-sectional geometry measured by MRI explained a proportion of variance in mechanical properties similar to that explained by pQCT bone cross-sectional geometry measurements and DXA measurements.
  
  
  CONCLUSIONS
  We found that there was a close association between geometry and mechanical properties regardless of the imaging modality (MRI or pQCT) used.
authors.affiliation: Department of Orthopaedics, University of British Columbia, Vancouver, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: S L
authors.initials: SL
authors.lastname: Manske
authors.forename: S A
authors.initials: SA
authors.lastname: Kontulainen
authors.forename: C
authors.initials: C
authors.lastname: Tang
authors.forename: P
authors.initials: P
authors.lastname: Guy
authors.forename: T R
authors.initials: TR
authors.lastname: Oxland
authors.forename: H A
authors.initials: HA
authors.lastname: McKay
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D018483:Diaphyses / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008954:Models, Biological; D011237:Predictive Value of Tests; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D016474:Weight-Bearing / Q000502:physiology*