title: Assessment of vertebral fracture risk and therapeutic effects of alendronate in postmenopausal women using a quantitative computed tomography-based nonlinear finite element method.
abstract: A QCT-based nonlinear FEM was used to assess vertebral strength and mechanical parameters in postmenopausal women. It had higher discriminatory power for vertebral fracture than aBMD and vBMD. Alendronate effects were detected at 3 months, and marked bone density increases were noted in juxta-cortical areas compared to inner trabecular areas.
  
  
  BACKGROUND
  QCT-based finite element method (QCT/FEM) can predict vertebral compressive strength ex vivo. This study aimed to assess vertebral fracture risk and alendronate effects on osteoporosis in vivo using QCT/FEM.
  
  
  METHODS
  Vertebral strength in 104 postmenopausal women was analyzed, and the discriminatory power for vertebral fracture was assessed cross-sectionally. Alendronate effects were also prospectively assessed in 33 patients with postmenopausal osteoporosis who were treated with alendronate for 1 year.
  
  
  RESULTS
  On the age and body weight adjusted logistic regression, vertebral strength had stronger discriminatory power for vertebral fracture (OR per SD change: 6.71) than areal BMD and volumetric BMD. The optimal point for the vertebral fracture threshold was 1.95 kN with 75.9% sensitivity and 78.7% specificity. At 3 months, vertebral strength significantly increased by 10.2% from baseline. The minimum principal strain distribution showed that the area of high fracture risk decreased. At 1 year, the density of the inner cancellous bone increased by 8.3%, while the density of the juxta-cortical area increased by 13.6%.
  
  
  CONCLUSIONS
  QCT/FEM had higher discriminatory power for vertebral fracture than BMD and detected alendronate effects at 3 months. Alendronate altered density distributions, thereby decreasing the area with a high fracture risk, resulting in increased vertebral strength.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Imai
authors.forename: I
authors.initials: I
authors.lastname: Ohnishi
authors.forename: T
authors.initials: T
authors.lastname: Matsumoto
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000627:therapeutic use*; D044466:Asian People; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D019245:Compressive Strength / Q000187:drug effects; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging*; D017698:Postmenopause; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016103:Spinal Fractures / Q000209:etiology / Q000517:prevention & control*; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D050071:Bone Density Conservation Agents; D019386:Alendronate
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