Damage initiation sites in osteoporotic and normal human cancellous bone.

Using a finite element (FE) method called biomechanical stereology, Wang et al. previously reported increased microcrack formation and propagation in bone samples from patients with a history of osteoporotic fracture as compared to normal subjects. In this study, we re-analyzed the data from Wang's report to determine the microscopic differences between bone tissue from osteoporotic patients and normal subjects that caused these different patterns of bone tissue damage between the groups. The morphological features examined were the number of "voids" (or osteocyte lacunae) visible and the distance of the lacunae from the initiation of the microcracks. We found that bone samples from patients with a history of osteoporotic fracture contained significantly more lacunae than normal control specimens. We also found a significant correlation (r² = 0.483, p = 0.001) between the number of lacunae visible in the image and the number of microcracks formed. These results help to explain the differences in total microcrack number between the osteoporotic and normal subjects reported in our previous work.