Degenerative disc and vertebral disease – basic sciences

This article summarizes the pathophysiology of spinal degeneration from a mechanistic basic sciences viewpoint, emphasizing the interdependence of discs and vertebrae. Intervertebral disc degeneration differs from normal ageing by involving physical disruption, typically in the form of annular fissures, prolapse or endplate fracture. Frustrated attempts to heal this large avascular tissue give rise to the typical biological features of disc degeneration. Discogenic pain appears to arise from the disc periphery as a result of nerve sensitization phenomena involving displaced nucleus pulposus. A degenerated disc loses pressure in the nucleus and bulges radially, like a flat tyre. This often leads to a transient segmental instability, which can be reversed by vertebral body osteophytosis. Annulus collapse in severe disc degeneration transfers substantial compressive load-bearing to the neural arch, leading to facet joint osteoarthritis, and possibly to degenerative scoliosis. The anterior vertebral body becomes relatively unloaded, and consequent bone loss increases the risk of anterior wedge deformities and senile kyphosis.