The vertebral fracture cascade in osteoporosis: a review of aetiopathogenesis

Once an initial vertebral fracture is sustained, the risk of subsequent vertebral fracture increases significantly. This phenomenon has been termed the “vertebral fracture cascade”. Mechanisms underlying this fracture cascade are inadequately understood, creating uncertainty in the clinical environment regarding prevention of further fractures. The cascade cannot be explained by low bone mass alone, suggesting that factors independent of this parameter contribute to its aetiopathogenesis. This review explores physiologic properties that may help to explain the vertebral fracture cascade. Differences in bone properties, including bone mineral density and bone quality, between individuals with and those without osteoporotic vertebral fractures are discussed. Evidence suggests that non-bone parameters differ between individuals with and those without osteoporotic vertebral fractures. Spinal properties, including vertebral macroarchitecture, intervertebral disc integrity, spinal curvature and spinal loading are compared in these groups of individuals. Cross-sectional studies also indicate that neurophysiologic properties, particularly trunk control and balance, are affected by the presence of a vertebral fracture. This review provides a synthesis of the literature to highlight the multi-factorial aetiopathogenesis of the vertebral fracture cascade. With a more comprehensive understanding of the mechanisms underlying this clinical problem, more effective preventative strategies may be developed to offset the fracture cascade.