[Prediction of vertebral strength using a CT based finite element method--clinical application in evaluation of the efficacy of alendronate]

QCT-based nonlinear finite element method(CT/FEM) can accurately predict vertebral compressive strength ex vivo. Alendronate effects were also prospectively assessed using CT/FEM in 33 patients with postmenopausal osteoporosis who were treated with alendronate at a dose of 5 mg/day for 1 year. At 3 months, vertebral strength significantly increased by 10.2% from baseline (p<0.0001). 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 8.8% (p=0.0013), while the density of the juxta-cortical area increased by 13.6% (p=0.0004). CT/FEM detected alendronate effects at 3 months. Alendronate altered density distributions, thereby decreasing the area with a high fracture risk, resulting in increased vertebral strength.