Heterogeneity of Bone Mineral Density and Fatigue Failure of Human Vertebrae

Bone qualities that are measurable via clinically available modalities and that can explain fracture risk beyond what is explainable by bone mineral density (BMD) are of significant interest. Evidence from literature suggests that the heterogeneity of BMD within a vertebra, in addition to the average BMD, may be an important determinant of the mechanical properties of a vertebra ^1–3 and risk of a clinical vertebral fracture ⁴. Much of the experimental evidence comes from tests, in which vertebrae are monotonically loaded and relates BMD heterogeneity to the quasi-static properties of a vertebra ^{1, 3}. The appearance of clinical vertebral fractures is in the form of progressive deformities indicating that fatigue processes are involved. However, the relationships between BMD heterogeneity and fatigue properties of a vertebra are not well-understood.