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    ASBMR 31st Annual Meeting

    Elastic Stiffness of Human Distal Tibia, Distal Radius, Proximal Femur, and Vertebral Body Assessed by HR-pQCT and cQCT-Based Finite Element Analyses Significantly Correlate with Each Other

    Category: Bone Biomechanics and Quality (Clinical)

    Poster Sessions, Presentation Number: SA0025
    Session: Poster Session I
    Saturday, September 12, 2009 12:00 AM - 12:00 AM, Colorado Convention Center, Exhibit Hall F

    * Xiaowei Liu, University of Pennsylvania, USA, Adi Cohen, Columbia University Medical Center, USA, Perry Yin, Columbia University, USA, Joan Lappe, Creighton University Osteoporosis Research Center, USA, Robert Recker, Creighton University, USA, Elizabeth Shane, Columbia University College of Physicians and Surgeons, USA, X Guo, Columbia University, USA

    Purpose: High-resolution peripheral quantitative computed tomography (HR-pQCT) and Micro Finite Element Analysis (µFEA) are emerging clinical tools that can provide measurements of mechanical properties at the distal radius and distal tibia. However, it is unclear whether and to what extent these peripheral measurements reflect the mechanical competence of the proximal femur and vertebral bodies, common sites of osteoporotic fractures. We therefore evaluated relationships between the elastic stiffness of the distal radius and tibia estimated by HR-pQCT-based µFEA with that of the proximal femur and lumbar spine, estimated from central quantitative computed tomography (cQCT)-based µFEA in the same human subjects.
    Methods: Of the 84 premenopausal women (aged 20-49) in this study, 60 underwent cQCT (GE LightSpeed 64 VCT, GE Healthcare) scans of the proximal femur, 62 underwent cQCT of lumbar spine, 60 had HR-pQCT (XtremeCT, Scanco Medical) scans of the distal radius, and 58 had HR-pQCT scans of the distal tibia. Based on HR-pQCT images, axial elastic stiffness was determined by µFEA for each distal tibia and radius with an isotropic voxel element size of 82 µm. For each set of cQCT images of lumbar vertebral body L1 and proximal femur, µFEA were performed with an anisotropic voxel element size of 0.937x0.937x2.5 mm3. A uniaxial compression displacement and a single-leg stance boundary condition was applied to each vertebral and femur model, respectively, to determine their elastic stiffness.
    Results: The mean stiffness values of the distal radius, distal tibia, vertebral body and proximal femur were 79.0±19.7, 222.1±52.6, 7.3±1.4, and 17.2±3.8 kN/mm, respectively. Positive and significant correlations (p<0.001) were found between the stiffness of the distal radius and tibia (r2=0.74), distal radius and L1 (r2=0.49), distal radius and proximal femur (r2=0.40), distal tibia and L1 (r2=0.37), distal tibia and proximal femur (r2=0.48), and between the proximal femur and L1 (r2=0.28).
    Conclusions: For the first time, the relationships between the mechanical competences of multiple skeletal sites were examined in vivo. Highest correlations were found between the stiffness of the distal radius and distal tibia, distal radius and L1, and between the distal tibia and proximal femur. These results indicate that the estimated mechanical competence of the distal radius and tibia assessed by HR-pQCT may be helpful in predicting vertebral and femoral mechanical properties.

    Disclosures: None

    * Presenting Authors(s): Xiaowei Liu, University of Pennsylvania, USA