抄録
Vertebral fracture of osteoporosis patients often lead to vertebral progressive collapse that results in a variety of comorbidities. Prediction of progressive collapse is so difficult that cancellous bone had characteristic stress-strain curves after yield stress. The purpose of this study was to reveal relationships between decreases in mechanical properties and structural indices of the cancellous bone as a model of progressive collapse with the cyclic compression test. A total of 15 cubic cancellous bone specimens were obtained from three regions of a 2-year-old bovine femur (n = 2): femoral head, neck, and proximal metaphysis. Structural indices of each specimen were determined using micro-computed tomography. Finally, deference of bone volume fraction (D BV/TV) between pre- and post- experiment was calculated with μCT. The specimens were then subjected to 5 cycles of uniaxial compressive loading from 0.3 mm displacement to unloading to 0.2 mm for five successive cycles. The decrease ratio of elastic modulus from baseline to fifth cycle was also correlated with BV/TV (r = 0.80, p < 0.01) and SMI (r = - 0.78, p < 0.01). The decrease ratio of yield stress from baseline to fifth cycle was strongly correlated with bone volume fraction (BV/TV, r = 0.96, p < 0.01) and structural model index (SMI, r = - 0.81, p < 0.01). D BV/TV were correlated with partial BVATV (P BV/TV) in under 35% and over 50% of P BV/TV groups (p < 0.01). Structural deterioration of cancellous bone is associated with the bone strength in progressive vertebral collapse.
